I'm not very Techy...but here goes...
On restart my computer went to a DOS screen with a "Windows could not start
because the following file is missing or corrupt: windows/system32/..." error
message

went through the chkdsk /r with the disc in the drive and it started the
set-up off the disc..thought I was well on my way...BUT now it is stuck in
the set up and says it can't find files and yes the disc is in!  I tried
cancelling, the computer restarts and goes right back to the set up, says it
can't find files,, wants the disc but nothing happens.

The disc I have is Windows Genuine Advantage Kit for Windows XP Professional
sent from MS because when my computer was repaired by a friend of a friend he
had installed a pirated version, so I purchased online