BleepingComputer.com: Can't boot into safe mode

Every time I try to boot into safe mode, it hangs on Mup.sys.. I can boot normally, which is weird.
I've tried googling but every solution doesn't work.
I've tried taking the Mup.sys file from another XP computer and replacing it but it didn't work.

My computer has Windows XP Home SP3

Its not too big of a deal because I don't desperately need into safe mode for anything but its still really annoying when I do.

Have you tried running chkdsk?

Sorry I haven't replied, I've been busy..
I ran chkdsk but the problems still happening.

Try the System File Checker:

How to Use SFC.EXE to Repair System Files

I hate this problem - because it is often a guessing game with lots of variables. There does not seem to be one single solution, so we can try to figure out your solution.

You say you only have the problem in Safe Mode so (to me), that rules out some suggestions I have heard before. I do see a trend in the hardware direction - PnP stuff, wireless adapters, SCSI cards, etc., so I think it is there, but don't know where for you.

I'll spare some details for now, but would you be so kind as to describe your keyboard and mouse arrangements? Wired, wireless, USB, PS2...

If you can recall, did it used to work in Safe Mode until one of those things might have gotten changed?

Do you you have any other PnP devices, memory "sticks", printers, mapped drives, external USB drives, high end video card or a SCSI card? Anything not "usual".

Unplug as many peripherals as possible, try to boot in Safe Mode and if/when it hangs, unplug mouse, keyboard. It may suddenly take off!

Try to unplug M&K, printer, etc., reboot numerous boring times, repeat until (hopefully) you can say something like - it works if I unplug my mouse or switch to a PS2 mouse, unplug my printer, don't have my stick plugged in, etc.

If you can figure out what it is, then you can fix it.

This post has been edited by joseibarra: 05 September 2009 - 05:02 PM

Thanks for the replies everyone.. I will try unplugging things.
My computer is a laptop but I have a USB mouse and keyboard with an external monitor. I'll try unplugging everything from it (keyboard, mouse, monitor, external harddrive, cooler) and try again.

Sorry I don't have a more scientific method!

This always seems to be a discovery chore - maybe somebody has some other methods to share.

Now I am getting more scientific.

I think the problem is not mup.sys, but what loads after mup.sys.

On two unbroken systems, one is nic1394.sys and the other is 18042prt.sys, and I found out what those are and don't really care (since I don't have the problem) but mine are related to KB, mouse and NIC. Hmmm...

Try to boot in Safe Mode again, except this time choose to Enable Boot Logging, your system will boot normally (hopefully) and produce a ntbtlog.txt file in C:\WINDOWS.

Look in the log file, find mup.sys and then the next driver that loads successfully. Some will not be loaded in between (at least for me).

My log matches what I see in a third party boot analysis program as i8042prt.sys, so the built in Windows logging mechanism seems to have about the same information - nothing to download.

When you find the next driver, look here in BC on the File Database section and see what it is and why it is. Something to do with some kind of KB/Mouse I/O or NIC stuff? If it is not there, Google it and find out what it is.

Then, find it on your system (probably in c:\windows\system32\drivers and check the version in the properites and see what you can discover about it with some Googling (Google is now a verb in the English language). Depending on what it is, there could be several options. Some Microsoft driver I bet.

Why won't it load in Safe Mode...

I am not sure what to do next, but I think you will now know what it is.

This post has been edited by joseibarra: 06 September 2009 - 07:04 AM

When i checked the boot log, there was a LOT not loaded after mup.sys
the first line that said "Loaded" after mup.sys is this:

Quote

Maybe the problem is all the drivers not loading in between? But if that is the problem I still don't get why it hangs only in safe mode.

Good job.

I have over 100 things that don't load between mup.sys and my i8042prt.sys. A repeating list of audio, video, sound stuff and I am not worried about it for the moment. For me, it is not a known problem.

My system loads usbohci, but several other things load first. I think yours is stopping there so I would like to look there.

It sort of fits - USB... = mouse, keyboard. Did you try the unplugging of USB devices?

If it is a laptop, you don't need a USB KB and mouse, right? Will it boot in Safe Mode with them disconnected?

Use the process of elimination with your USB devices.

Browsing to mu USBOHCI.SYS in the c:\windows\system32\drivers folder, I find version 5.1.2600.5512. But I am running XP Pro, so I don't know (yet) if there is a difference. What is your version?

Budapest suggested sfc /scannow, which will not hurt anything. You will need an XP installation CD with SP3 on it or you will find it very annoying. Usually, these have to be made by hand (highly recommended), but you can replace the file yourself.

That file falls under the protection of Windows File protection, but you could can find (Search) for a copy on your system.

Your USBOHCI.SYS may be compromised by malicious software.

Download, install, update and do a full scan with these free malware detection programs:

Malwarebytes (MBAM): http://malwarebytes.org/
SUPERAntiSpyware: (SAS): http://www.superantispyware.com/

They can be uninstalled later if desired.

Delete the file and Windows File Protection should replace it silently and quickly, or replace it yourself. Reboot, etc.

Other things I read about involve BIOS upgrades, BIOS clearing, BIOS flashings, but at least the flashing has some risk.

Some BIOS can just have the extended part cleared and then it resets itself automatically. Helpful when USB devices act up or hardware has changed. Do you have another KB/mouse to try?

What is your hardware and BIOS information?

Look at their WWW page and see if they know about Safe Mode issues - especially with external KB and mouse.

Can you check to see what is the latest and if you can just clear the BIOS extended data area which will reset itself (this has some USB info in it).

This post has been edited by joseibarra: 06 September 2009 - 03:35 PM