If you could post a crash log that would help.
I would try a test user account Isolating an issue by using another user account
and boot into your recovery partition and repair your hard drive When to Run First Aid in Mountain Lion's Disk Utility - For Dummies
and use Disk Utility to repair permissions About Disk Utility's Repair Disk Permissions feature
and if that doesn't work, back up your office documents, uninstall Office, and then try reinstalling it