I have a 300gb IDE Maxtor hard drive that had XP Pro and a bunch of data on it. XP got corrupted and wouldn't boot with a "Windows could not start because the file is missing or corrupt..." error. The file was pci.sys. I tried to re-install just that file but I got a "access denied" when in recover console. If I tried to browse to that directory, it said "invalid directory" or something similar. So I went to do a repair install, but I didn't know it was an SP1 disc that the PC's owner gave me, so it started the install but changed the drive to a 128gb partition (unbeknownst to me), and then the install crashed due to a bad motherboard (which probably caused the first problems). So, to make sure the data was still intact, I booted to a UBCD4Win and quickly explored the drive and all was well. I ran some RAM diagnostics and some other things, then shut it down. This was Saturday. So today I installed a new mobo, and went to do a repair install, and suddenly the hard drive is being reported as unformatted or unrecognized. WTF?!?!? So I attached an old 10gb I had laying around, installed XP to it, slaved the 300gb, and sure enough, it is now unformatted. So I'm currently running a data recovery program to save the data. What the heck happened?!?!? Could it be that the bad motherboard has jammed up the file system so that it will only read correctly on that mobo? The data is there, the recovery program is gettng it, but it will take hours. Any ideas????