Waveform Editor freezes up

After a decade of happily using AA, I'm starting to encounter an issue where after recording something, I'll try to edit, and after a couple actions, the edit window will suddenly freeze up. That is, I can move the cursor but cannot click/select on the waveform itself. Nor will the keyboard respond (can't play audio). I can, however, open and click on menu items. I usually open a fresh track and start over as the issue doesn't occur consistently. Any ideas? Thanks!