You won't get anywhere with the BIOS, I'm thinking that your hard drive got damaged, or was damaged before you tried to do the disk cleanup. Windows will work around drive errors by marking sectors bad as it finds them and ignoring them. The issue with that, is that sometimes this just hides things for a while till something tries to read or write to the bad part of the disk and you get a crash.
Go into the BIOS and see if there is a drive check utility there, or S.M.A.R.T disk reporting, you can probably get at least some info about the hard drive with that. Not saying that your drive is bad for sure, just have seen "missing" file errors way too many times that were caused by a bad hard drive rather than some Windows OS issue.
Also, why don't you try what the message tells you and try to do a Repair from the XP disk? Just don't do a full restore yet, that's usually the very last thing to do and only after you get the data out of your drive using another PC. Plus if the drive is going bad, you would want to buy a new one first.