rev opens and then disappears spontaneously

[Jon]

All of a sudden, Rev no longer works.  I try to start it, it pops up, 
all of the windows appear, and then it spontaneously disappears.

There are no hidden Rev processes running.

I had been using Constellation, but turned it off (or tried to?)

I have not yet re-booted (too much else going on right now).

Anyone seen this before?  Is there some file I can clear or something?

:)

Jon