How can I fix the Microsoft Error Reporting?

I don't remember this problem occurring so often with OS X 10.5. Frequently (approximately 8 times out of 10), when I try to shut down the computer, I get the error message "The application Microsoft Error Reporting canceled shut down". This problem occurs with my MacBook (that I mostly use), but also with my iMac. A subsequent box says: "Microsoft Word has encountered a problem and needs to close. We are sorry for the inconvenience". I then usually click the button to send a report to Microsoft and shut down my computer. I have tried disk utility's repair permissions, but the problem still carries on.

I've ignored this for a while, because it just takes a couple of extra clicks to shut down. I also thought the next Microsoft update would solve it (I have version 12.2.5), but - no change. I hope it's not some kind of Microsoft virus...