I had this problem with office 2003 it kept crashing and spent quite some time looking through forums for an answer. I know that many are already using Office 2007 or Office 2010. But I am still using Office 2003 and I am sure that many are as well 
I was going to uninstall all the drivers that I thought could be causing this problem, one by one but lucky for me I manage to pick the culprit driver in the first go hehehe talk about luck. I finally found the answer to my problem and it was the latest Bluetooth with Enhanced Data Rate Software II drivers for Lenovo T61 thinkpad.
So if you are experiencing something similar then I suggest that you uninstall the driver mentioned above. In some cases there might be other drivers that could be causing the same problem.
Good luck