|Sounds like a hard drive problem.|
Did you do a clean format before installing the OS?
If yes then I suggest you download the hard drive test utility from your Hard disk manufacturers website and run diagnostics on your hard drive to eliminate the possibility of it being the hard drive.
Another possible option:
If the PC has a floppy drive then get a windows 98SE floppy and use it to fdisk and format the hard drive. NOTE - This means using FAT32.
If there are bad sectors on the hard drive or it is bad then the format attempt will fail or give you periodic attempting to recover messages as it encounters bad sectors. At least this way you will get to visually confirm the state of the hard drive. If the format is successfull then you can use the WinXP CVD/DVD to install the OS without formatting the drive again.
☺ When everything else fails, read the instructions.