This problem involves a Dell Optiplex GX620 (small form factor), and my old friend Windows XP Pro.
This computer boots up through the BIOS without much ado, but when it hits the first Windows screen, it hangs like a side of beef at Peter Lugers.
The first thing I tried was running a chkdsk /r. This took a while, but found no problems.
After restarting the computer, I attempted to enter "Safe Mode with Networking", but the process hung at the following line "...\System32\Drivers\Mup.sys.
Another restart and the boot was successful when I selected "Safe Mode" (without the Networking).
Because of the inablility of the computer to boot using the choice "Safe Mode with Networking", I thought the problem might have been with loading the drivers for either the ethernet or wireless connection and disabled those devices while in safe mode...still no luck.
I have tried a different hard drive, imaged the same way the original hard drive was and yet another hard drive with Windows XP loaded from an original XP CD -- all with the same lack of results.
Let me know if you feel my pain.