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Mup.sys hangs and other Windows lockups that freeze your system during boot up can be the most frustrating issues. Unfortunately the mup.sys hang, which you can only see in a safemode boot, has many causes as related in our web article, troubleshooting the mup.sys hang. As such it also has a myriad of solutions. One webpage can only go into so much detail, but fortunately ... We have a great user community that loves to share their resolutions and experiences particularly in regard to the dreaded mup.sys hang. To serve you better we have created this page to share their unique solutions with you. Please note that all comments are welcome and appreciated. As we respect your privacy, We will only post resolutions here after we have explicit permission to do so by the submitter. If you would like to share your own experience, please send us the pertinent information by using our Contact form. Please feel free to include as much detail as you like. To enable us to contact you in case of any questions or if you would want a reply back, please include your email in the provided field. Of course, we will keep your email address confidential. An email address is not required however and will not affect consideration of your submission. You can specify a name, nickname, initials or whatever you want for identification or if you want to remain anonymous that is fine too. Just let us know. Note that we will not use personal email addresses on your published feedback as that is against our privacy policy. It is our goal to provide you with the best information to help resolve your issues and your input is most valuable. We sincerely thank you for visiting our site and very much appreciate your interest and participation.
MUP.sys article was extremely useful, pointing at a power supply overload. I had recently installed a second hard drive with XP loaded because the first one became corrupted in a couple of sectors that could not be repaired and it became unstable. Unplugging the old hard drive fixed the problem immediately. - anonymous I found this problem (mup.sys hang) to be hardware related, specifically... Power Supply. Not anything to do with Mup.sys at all. I had a Power Supply Fail completely in an old P3 1GHz Dual Processor system, also with several SCSI drives. I replaced the power supply with an old 350W ATX job from another old relic, and that's when I noticed the problem. I tried removing just about everything, but it wasn't until I disconnected one of the SCSI HDD's that the problem was solved. It's obvious to me now that the power supply could not supply the current to all the devices, without a voltage drop which caused the system to hang. I hope this helps out some people with their Mup.sys related / unrelated problems. Thanks to your forum I may have saved quite some time, frustratingly repairing Windows drivers thinking that software was to blame. - Regards, Brett Gold Coast, Australia I had run across this problem (mup.sys hang) on my desktop last spring. I was able to get back into the computer by entering the Repair area after booting from the XP installation disk and running CHKDSK. That took several attempts. Then, CHKDSK ran very, very slowly. I then rebooted via SAFE MODE (again running very, very slowly), eventually making some repairs and getting past the problem. Ultimately, I had to change the power supply in order to return the computer to dependable operation, though the mup.sys problem never showed again. Was there an association between the mup.sys issue and the power supply or not? Who knows? My power supply was deteriorating, though I did not know it. It was very frustrating to pin down the bad power supply, as normally it would run everything just fine. However, as its failure progressed, it began to reveal itself at times of maximum power consumption. My suspicion is that the initial mup.sys issue surfaced when computer did not power down successfully due to a power failure and a file (or files) was (were) left hanging. Again, Thanks, - TomBob Thanks very much for your troubleshooting procedures for mup.sys. It apparently was the power supply. Just could not handle the extra hardware when it was called up by mup.sys. - anonymous
Our issue turned out to be a bad memory sector in the onboard nVidia graphics. I ran Dell's video memory test diagnostic at startup to find the error. I reported the error code to Dell, which minimized call time. A tech was dispatched to install a new [mother]board to resolve the issue. Thanks for posting the checklist; it helped. - IT Director I just removed my USB cable conection to the modem, and the system recovered from the "mup stop". It was easy after reading your lessons. I think the problem started with a Windows Installer 3.1 version. I donīt know why windows support installs it , if itīs not recommended. The real good one is the 3.1 "v2". [Note: My USB] connection goes to a HUAWEI modem that doesnīt work properly if two machines are connected (and I have two so this must be actually the problem generator) - Thanks, GPF My MUP.SYS hang actually ended up not being a "hang" but an extremely (and I do mean extremely) slow boot up. It would get to MUP.SYS and sit there for about 30 minutes. In my case it ended up being a problem with the hard drive. I have an HP DC5850 computer, with a 160GB Seagate hard drive (Model Number ST3160318AS). To fix the problem I installed the firmware update (VERSION: HP4LS Rev. B) for the hard drive from HP's website - William
CHKDSK /P /R The synopsis was that the machine would get to the Windows opening screen and before loading it would lock up, the monitor would go to sleep and the hard drive would go idle. By trying to load Windows XP in safe mode I saw that the system locked with the last line displayed as Mup.sys. This file is not the issue. By configuring my Bios so I could boot via a Windows XP Install disc, I was able to load the Windows Repair Console. Once I received the C: (DOS prompt) I entered CHKDSK /P /R and waited for the process to be completed. This took quite a while so be patient! The issue was that there was a bad sector on the hard disc that had corrupted data. This bad spot was now marked and repaired by CHKDSK. Still in the recovery console I entered the command FIXBOOT at the C:\ prompt and waited for that process to be completed. Once that process finished, I entered the EXIT command to leave the Repair Console and rebooted the PC. The first boot took a little while longer than normal, but when the machine came to life nothing was lost! This procedure recovered the machine and everything is working normally. - Submitted by Don W. Thank you for the fine information on this problem. I used your checklist, but no luck. Then I tried your troubleshooting suggestion #11. I booted from the installation CD, selected "R" for Restore and at the command prompt I ran "chkdsk /p /r". It took about an hour and reported that it had repaired some errors. I rebooted the computer and the system works just fine now. The information on your website saved me many hours of searching, testing and reinstalling. Thank you! - Resolution feedback by Lorrin Thanks so much for your instructions on how to get a computer back up and running after a safe boot freeze at mup.sys. This happened to me after installing a new Logitech webcam today and I was dumbfounded for hours. Fortunately, I was able to resolve my problem by running chkdsk - thankfully. Of course, finding the XP CD and remebering the password were another story, but it taught me a good lesson. Thanks again. Your instructions were easy to follow and worked great. - Anonomyous nVIDIA forceware network access manager software created this hangup for me when installed....uninstalled it and no problems..reinstalled it and problems...uninstall and all ok....only issue with SP2...go figure! [Followup] Prob returned but only on cold boot - So...this is what I did now and have not had the problem again. Do this only in DOS mode, not within Windows OS or from recovery console. You literaly need to be in DOS mode (boot from floppy w/cdsupport). It appears the MUP.sys files loads even during Windows recovery setup! The MUP.sys file is in windows\system32 folder. Might also be in main windows directory((i deleted mine from main Windows folder and kept it in system32 folder. I expanded the mup.sy_ from the cdrom (I386 folder) to this folder and overwrote it. Then I set the attribute to +r. So, what ever the problem was, something was overwritting the file. Setting it (mup.sys) to +r seem to "lock" it and its been stable since. Since it is now a +r state, I have not had any file failures related to programs or event errors trying to use this file or an other funny Windows glitches! - Anonomyous Topic: mup.sys Error System failed to restart Hi we discovered that we had incorrect drivers for the SATA drives and the system kept rebooting with (mup.sys) system failed to start ERROR MESSAGE. [This was] a driver issue, if you get the drivers right the problem should go [away]. - Regards, AK -- Many thanks to all for the valuable feedback and resolutions! -- www.AITechSolutions.net Webmaster
The following are comments from some of those whose mup.sys hang was caused by a corrupted registry. These issues were sucessfully resolved by using our manual registry restore procedure. Your windows recovery repair to restore the registry just saved my a$$! I wanted to say a thousand thanks to you guys!! Everything was great- The way you wrote it up to precision of the write up. KUDOS! I bookmarked it in case I need it in the future. You guys ROCK! thanks again!!! - Anonomyous The article on how to boot my xp machine was the most useful article I have ever used. It was totally idiot proof, and I needed that. Thank you for the fantastic help. - Anonomyous I was having the 'mup.sys' boot failure for a while now and I found this guide on your web site. I did the manual registry replacement and it worked! The only problem I had was that I needed to re-verify Windows afterwards but its working again! Really saved me a hassle since I have lost my install disc and used my wifes to do the restore. Thanks for the great article! - Submittted by Jarrod P. I just finished getting my XP laptop computer going again after a registry problem kept it from booting past the mup.sys file. I would like to sincerely thank you for your assistance. I had just about reached the point of reinstalling XP, the solution for the impatient -- and sometimes the only solution -- but felt I could find some help somewhere. Your article and instructions were invaluable. Thank you, - TomBob THANK YOU THANK YOU THANK YOU !!!!!!! This is a very well laid out set of instructions for even the pc novice to follow, and saved me from a tremendous headache of trying to salvage something of my non-booting hard drive. This worked flawlessly. BTW, did I say THANK YOU?!!! Huge :-) - Anonomyous XP won't boot? - Performing a manual restore of the Windows XP registry Very good instructions. I used bartPE instead of restore console but it (your procedure) works like a charm. - Anonomyous THANK YOU!! This (manual restore procedure) resolved my very troublesome problem. Great fix, much appreciated. - Submitted by Dan I just have to say thank you sooooo much for the [Manual Registry Restore] article. I allowed winxp auto updater to install several security patches this morning, and ended up with the dreaded mup.sys error. I had also installed new memory and a new printer yesterday (although the system restarted fine several times during and after all that), so I had a lot of things to check out as far as what went wrong. Nothing else worked, so I decided to try this solution. And...even after doing what this article recommends, I was unable to boot up. BUT!!! I then allowed the XP install disk to repair my OS, reinstalled sp3, and then...used the instructions from this article to put my old registry back in place. And voila!!! Everything seems to work! No need to reinstall all the devices and software! Phew!!! I can only assume that some random system file was corrupted..live and learn! So thanks for the help. It would have been a week of work instead of a day without these very clear instructions on how to work with the recovery console. - DLR
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