Intermittent problems are always tough to diagnose.


Next time, try starting Word in safe mode and see if that helps. If it does, write back here and someone will walk you through what to do.

Open Office apps in safe mode on a Windows PC - Microsoft Office
Repair an Office application - Office Support

Thanks. However, I was able to "fix" it by just shutting and reopening Word. I still have absolutely no idea however why the "merge" mode began. Guess I never will. It's just darned annoying that something as random as that would happen. I had done nothing different.

Appreciate both of you for the attempts to help though. "When in doubt, reboot" always seems to work.