Why is Text Edit Suddenly Failing to Open?

Beginning yesterday, when I tried to open a simple text file Text Edit refused to do anything. It showed up in my Activity Monitor as "Not Responding". So I've forced quit it numerous times, restarted, ran disk utility, reset PRAM, etc, etc. etc... I've run out of ideas, and am stumped as to why something this basic, which has worked fine for decades, has decided to go on strike. Any suggestions?