based on the way he fixed the problem, I would suggest that there is an existing corrupted installer file cache on the machine, probably left over from the pre-crash software.
My guess would be that the local computer man didn't do a proper reformat / reinstall, but instead simply overinstalled another copy of Windows, leaving orphaned files scattered around the hard drive. That would cause these symptoms, and allow the fix of "cdcache=0" which forces the install direct from the CD and not from a hard drive file repository
I would expect future problems with other programs