Here's my situation:For months my computer had been working just fine... then for no reason, just out of the blue, Win XP failed to start (Safe Mode showed it would stop at Mup.sys)So I ended up reinstalling... and it was fine until about a week later when I had the same thing happen.Long story short, this is a very regular thing for me now... it will just randomly fail to boot anywhere from 2 days up to 3 or 4 weeks later.I even tried Windows Vista, which worked great until... you guessed it... it crashed and refused to start up in any mode (normal, safe, etc)Now, when I reinstalled Windows, it never even booted up... before it ever started windows for the first time, I get a registry error (which is among the several random errors I get)Tried installing Vista... same result. It never booted up... just gave me a registry error right off the bat.Tried XP again... same thing. So what is going on? Why am I getting horrendously unreliable results now? My thoughts are that its hardware related but I have no idea what it could be.Any ideas?

Todd,Have you checked your drive(s) and memory health, could be that either one is crapping out on ya. Seeing how after a reinstall results were the same, we can rule out spycrap. Just check your HD maker, seagate, wd or whatever you have, for a check tool, also run memtest (run it the whole night and see in the morning if you have any errors) http://www.memtest86.com/

Well I dont think its the drives because I've tried a brand new hard drive that I had extra from a previous build, and it was doing the same thing. It could be the memory though. I have two sticks so maybe I should run the test and also try running on one or the other.Could it have anything to do with the CPU at all?Troubleshooting computers suck... :-lolThanks for the input!

I'm guessing you may have googled mup.sys as I just did...You may have already seen this??:http://www.hardwareanalysis.com/content/topic/31874/Long post...Lots-O-Reading...I did't read very much of it...Just seemed like a good source of info that may help you out??...See page(3)(half way down or so)..A post by Bobb Fwed...If you havn't googled your problem...I'd like to suggest you do...There is allot of info on your subject...The cures seem to be widely varied...Good Luck!!

The problem with mup.sys is that usually mup.sys isnt the problem... its the last file loaded before the problem crops up, so most people tend to think that mup.sys is causing the problem. Its just a networking file from what I understand... not a critical system file. Its a tricky thing but it makes sense if you think about it. I don't believe it has anything to do with mup.sys because I've tried disabling it and it gives me a registry error, something along the lines of "that doesnt even exist". So... its got to be something messing up my hard drive or the files somehow... because even Windows Vista will do a hard crash on me (I can't even install it because it will crash before it boots... never did that before) So I seriously seriously doubt it's software related. I think it's hardware... question is... what hardware?

Right...In my few minutes of reading I realized mup.sys isn't the actual problem...(Someone mentioned NDIS.SYS is the next file to load??)I was surprised to see the variety of problems that can cause this...And the Variety of fixes...Very interesting...I think I'd start with the Clearing of Cmos like that guy Bobb Fewd stated...Did you read his post?? If that doesn't help..then a flash to a latest bios if necc...Something in an XP SPII update was acting goofy...Some bad recource code or something..Oh well.Easier to copy and paset his post than for me to attempt to explain..he he:(Copy and Pasted from Hardware Analsys Forums)Bobb Fwed Mar 16, 2005, 04:02 PM Message - Profile - Add Buddy - Alert ModeratorsRe: Windows xp freezes at mup.sysREAD THIS POST FIRST, THIS IS THE OFFICIAL SOLUTION, INFO FROM MICROSOFT!!I spent a few hours reading through posts and forums on the net. I finally found that this seems to be a known Windows XP SP2 - motherboard issue.Mup.sys is not the culprate, it's just the last file before resources are alocated for WinXP.With the latest service pack there were some resource code rewritten (theoretically for security reasons). Due to this, mobos that have certain resource sets become invalid sometime after SP2 is installed (note: it may not be right away). All that needs to happen on most mobos is for this resource set (the ESCD) to be rewritten. Most "higher-end" motherboards have a setting in the BIOS to say "rewrite ESCD next startup", but not all do.My motherboard did have that option, but it didn't seem to work anyway.So the next step would be just to reset the BIOS. All motherboards have a way to do this. Most boards will have a jumper near the battery with which you can do this. Turn off the power on the power suply. Move the jumper over to bridge pin 2 and 3, turn on power suply for 10-15 seconds (if you hit the power button nothing should happen -- that is a good test to see if it is doing what it is supposed to be doing). Turn the power off, wait 10-15 seconds, switch the jumper back to bridge pin 1 and 2. Turn on power, hit power button, your problems should be fixed.If they are not, your ESCD may be hard coded somehow. The next step is to try to flash your BIOS with the newest version of your BIOS. Check your manual for all the instructions for that (or I'm sure there are plenty of forums that can describe how to do that).(End of Copy and Paste)*Comment on above Post!!* I'm thinkin you may build your own stuff?? Not sure..but you made a comment along thise lines...If so then you know how to clear cmos and flash bios..ect...If your NOT Familiar with those processes please *Consult Your Perticular Motherboard Manuel for Instructions on Clearing Cmos or Flashing Bios!!*This guy makes a blanket statement that does not apply to all motherboards...ie: with any Asus motherboard I have ever owned...You Never Turn the Power Supply on with the jumper in the Clear Cmos position!! I personally would never Attempt to "Test" that either!!...In some instances it is required you remove the Cmos Battery before moving the Jumper to the Clear Cmos position...In any case..Just follow your Motherbaords Instructions!!Anyhow...That just sounded like a good place to start if you havn't already done so?? I seemed like a few folks had their problems resolved after a simple clearing of Cmos...That would be nice Huh!!If not I hoped you may find the Golden Egg somewhare in those posts..Good Luck!!