No idea, Ernie, but lesson I have learned and SEEMS to work, is "when in doubt...reinstall the bugger." Reinstalling SWB should take all of 10 minutes. If it still happens, then, ATLEAST, you know you are not getting tripped by an install that has gone loco on you from a fragged download etc....
Actor Kevin Kline was asked once (Actor's Studio) how he can play his comedy rolls with such repeated and consistent passion. His response:
"I don't know, I just can't imagine not being happy."