Hi Jerry,
Have a look in the Windows Event log. The installer should have created an entry if it ran into a problem.
Until recently, we were also running XI on Windows 2008 but I've never had to rollback a server and reinstall Crystal. This sounds more like a conflict than permissions. Process Monitor should help tell you if the problem is with a specific module.
The installer creates a log file. Search the Business Objects folders for *.log. The last entry should be what it's trying to copy. Hopefully it trapped the problem as well.
Good luck,
Brian