Heres a part of an article by a MSCE on this error.
A post by Sean Branham at the Annoyances.org web site. See the full text of the thread at http://www.annoyance...nxp/t1047532372
Sean correctly determined that the cause of all these disparate "hung at Mup.sys" failures were actually caused by problem with the Extended System Configuration Data (ESCD) stored in the system BIOS.
The ESCD maintains a static list of Plug-and-Play resource allocations. This avoids recalculating all the allocations at each restart. If the ESCD gets corrupted, then the operating system cannot assign resources correctly. Windows makes this resource decision just after it loads the Mup.sys driver because that's when it loads the Advanced Configuration and Power Interface (ACPI) drivers.
You can download the (mercifully short) ESCD specification from http://download.micr...f3456c/escd.rtf
Once we knew that something in BIOS might be causing the problem, solving it was a snap. We downloaded the most current firmware revision from Dell's web site and flashed the BIOS and that was that. (Some motherboards come with an ESCD rebuild option in CMOS, so it would not be necessary to flash the BIOS.) The system booted without a hitch and performance was right back to where it had been before the problems started. If it hadn't been for Sean's insight, we would have spent time and money replacing the PERC controller, which unfortunately might well have solved the problem because replacing the board would have refreshed the ESCD.
It's difficult to determine whether the system crash earlier in the week caused the ESCD problem or vice-versa, or if some other problem caused both. At this point, Anon is going to keep an eye on the system and hope for the best.
I hope you see that it is not a mup.sys error because mup.sys is the driver for the Multiple UNC Provider, which determines which network client protocol to use when the target server is specified by a UNC path such as \\Server_Name. The real error is the file that loads after mup.sys.
The first thing you should try to do is reset your cmos( bios) back to default with the jumper on the motherboard. If you still have the problem it may be a conflict with the drivers. Look in device manager for any conflicting hardware. I have read where bad memory and moving the PCI cards around in the computer have also caused the problem, but i take those with a grain of salt.