|To save info on hard drive use either of the following:|
1- move hard drive into another computer as an extra drive and copy important files.
2- boot to a linux CD (do not install) and save files to removable media. (set BIOS to CD as first in boot order)
After saving your files, use XP disk to format drive and reinstall windows, then update windows (as many times as it takes to complete), update drivers, then install programs, and replace copies of your files back.
If you have any problem installing, check RAM with Memtest.
And test hard drive with HD mfg.'s testing utility.