siryl, I'm having the same issue right now. I'm currently booted up using Hiren's Boot CD and copying all my files to a usb backup drive so I can do a clean install after a format. I've read alot of mixed reviews on this problem the last few days ranging from needing to reseat things to the windows registry getting cluttered and fubarring. Someone even claimed that they got theirs running after unplugging all USB peripherals when it hangs on mups.sys. None of this worked for me so I'm just going to give the drives a well deserved Summers Eve treatment and reinstall.
The boot/utility CD I'm using is Hiren's Boot CD - http://www.hiren.info/pages/bootcd
It recognizes both my RAID 0 drive array and the USB backup drive. Once booted I'm using NTFS Dos Pro 5.0 to get to a DOS prompt and then I used xxcopy (an xcopy clone) to copy the files. It's been copying all night (only 100 gigs) which is slow slow slow but it's better than losing it all possibly. I believe it's copying at a rate of approx. 1 meg every 8 seconds so that's relatively slow over a USB 2.0 connection. anyway, give that a try if you can get it booted. The Windows XP Recovery Console DOS environment does not offer the xcopy command, only the copy command, so unless you want to manually do it forlder by folder you have to use a 3rd party boot/util CD. Ultimate Boot CD
is another one that may work, however, it wouldn't read my RAID 0 array so I had to resort to Hiren's which I think is better.
Once I get the files copied I'm going to experiment a bit to try and fix it and then do a fresh install regardless.