A few days ago my wife got the strangest error: she could no longer save an invoice in Quickbooks 2011 Pro as a PDF. Usually, this is a UE problem. But I tried and got the same results. I tried restarting Quickbooks, and even rebooting, but no saving and no printing. Hmmm.
After consulting Mr. Google, I found a forum post linking to the following page:
After following step #1 the saving worked.
Hopefully this helps someone else out down the road.