Windows XP stuck on loading screen

Dell laptop running Windows XP Home.  When you turn it on, it will not get past the Windows XP loading screen, with the animated progress bar.  It will sit on that screen and never proceed.  Safe mode (any style) sticks after loading Mup.sys.  Last know good configuration results in the same.  I ran a virus scan using a rescue disk and nothing was found.  I have disabled all on-board hardware in the bios to no avail.  I have inserted the XP disk an upgrade to XP Pro to no avail.  I cannot find a way to run sfc, but would like to if possible.

Not wanting to reload from scratch because of the custom software installed.

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mup.sys is for network functions and usually the problem is not related to this driver. Have you checked this:
Steven CarnahanNetwork ManagerCommented:
A few years ago there was a discussion about this issue on PCReview:

and an even older thread on

Both of these appear to match what you are describing.
I had this kind of problem twice and I fixed it by resetting the BIOS to factory defaults (default values).
Windows (xp) cound not start because the following file is missing or corrupt \windows\system32\config\system

Disregard the title, but it is a process to manually restore the system's registry......I would restore all the hives.....

Also, UBCD has Memtest on it.... Let it run for about an hour or two (overnight would be ideal)...

Ultimate Boot CD - Overview

I would also double check the HDD with the Manufacturer's util on the UBCD as well....

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Windows XP

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