My laptop running xp hangs on booting after it loads Mup.sys. It also hangs when I boot from the windows cd, so I have no idea how to fix this, unless it's a hardware problem. This happened out of the blue today (no recent hardware or software changes). I found an earlier thread here that reported what seems like a similar problem: http://www.computing.net/windows2000/wwwboard/forum/37902.html but didn't see anything that helped. My system is a Dell Inspiron 2500, about a year old, as delived by the manufacturer (897 celeron, 64 Mb Ram, 9.4 Gig IDE harddrive, windows xp home 5.1.2600).

After MUP receives responses from all the redirectors, it evaluates those responses and sends the UNC request to the redirector that has located the resource. If more than one redirector locates the resource, the redirector with the highest priority receives the request. (You set the redirector priorities in the Network Access Order field of the Network Control Panel's Services screen. By default, the first client you install on the system receives the highest priority.) Check your settings in Your Network Control Services Panel.The mup.sys is being redirected causing delays. Make sure you have sp1 in.

My problem is I can't get anything up and running to check or change any settings: safe mode hangs after loading mup.sys; I can access BIOS to boot from the xp cd, but it also hangs before getting to the setup screen. Unless I'm doing something wrong, I can't even get to the recovery console to try and repair things.

OK try this.. Go into your bios and make sure you have the settings set to enable APIC not PIC. This may have been due to Bios Upgrade or resetting it to system defaults when you were trying to start your computer. You will then have to boot to the cd and reinstall xp. The ACPI has to be enabled during the install.You cant just fix it without reinstalling xp. Hope this helps

I'm having the same exact problem. I don't remember installing any updates or any software.. my computer just doesn't want to get past mup.sys. It won't even go through safe mode.. I even tried the recovery console, but I wasn't able to do much. It seems to hang at mup.sys or just after it.. won't get into windows. I'm running an old Celeron 400mhz w/ 160mb.. XP PRO