Can you add the OS you are using and the Windchill Version? Tech support might have some more ideas on this one, but try looking at the Add-ins in Office to see if the "PTC Office Add-in" is listed and if it is listed in the Disabled section? If so, try enabling it. This Add-in should get installed and registred in Office as part of the installation process.
Hmm, my next thought is Microsoft Office Repair. Go to Add/Remove Programs and run the Repair option for MS Office? Is there any languages involved, or is everything in English. If that does not resolve it, you'll have to work with PTC technical support. There's gotta be something unique on this machine, like a conflicting Office Add-in, security software, custom Windows configuration, etc. Last thing I would try is run the application as a full admin and a regular user to see if there is any difference.