We've seen issues with Microsoft Office for Mac (in Word, PowerPoint and Entourage) a few times recently at several client locations.
If an Office application is crashing, when the Microsoft Office crash dialogue box comes up, open the "View detailed report" window. If you see the failing module as "JapaneseProofing.tool", then...
- Navigate to Microsoft Office Applications folder/Office/Shared Applications/Proofing tools.
- Remove Japanese, relaunch Office apps (no restart needed, etc...).
This fix has worked for us several times. Please let us know what your experience is or if you have more information on what is causing this.