|When you say they are listed under program files do you mean the folder C:\Program Files or do you mean under the program listing in the Start menu?|
Typically you don't see individual apps (e.g. PowerPoint and Excel) in C:\Program Files, you would see a Microsoft Office folder and then a few sub-folders deeper you find the .exe files for each app.
If you meant a listing under the Start menu, are you sure they are not just short-cuts - shorts that don't actually work?
Assuming it's a valid copy of both, why not call MS support and get their advice?