XP pro not installing

Hi all.
My mate is having trouble repairing his XP pro OS.
It starts the process but gets to a certain point and it tells him it can't continue as there is a file missing.
I thought that was the whole point of the repair, to replace anything that was corrupt or missing?
The reason he was having to do this in the first place was hitting the big red button instead of shutting down properly.
What has he done and can it be fixed?
Cheers.

 

This is just a possible cause for this problem, it can be on most occasions bad memory in the pc.

 

Thanks for that suggestion, i will let him know.

 

If Dewey's solution doesn't work - Posting some more exact details of error messages, symptoms and systems specs would help diagnosis.

 

Hi.
Just to let you know the problem is sorted.
I loaned him my disk and it repaired it without a hitch!
His disk isn't damaged or dirty so don't know what went on there!!
Cheers