The error has nothing to do with BIOS. It's a Windows error.
The BIOS key on a Dell is usually F2 I believe.
Sounds like the registry is corrupt. I assume this is WinXP?
You should be able to restore the damaged hive file from an earlier backup of the registry using the Recovery console. Instructions here:
http://www.kellys-korner-xp.com/xp_sys32.htm
If that fails then you can try a repair installation of windows. Boot from the XP CD, press Enter at the first menu, then the menu after the EULA agreement select "Repair".
This forces Windows to do a re-install. You won't lose any dat or installed apps, but you will need to install SP-1 (if it's not on the original install CD) and all the Critical updates.
HOWEVER, I'd also be concerned as to what caused this. Could be the HDD is dying and that's what corrupted it. Could also be a virus. Could have just been a fluke.
Did your friend give you any history as to what led up to this?
Last resort is a format if the repair doesn't work, but you'll want to try connecting the drive as a spare on another computer to copy his data off of it first.
Hope this helps...