2.54b only displays one window at a time.

I am running 2.54b, and for reasons I don’t fully understand, I can only view a given window while I actually have the mouse cursor over it (and if the tooltip shows up for an item, everything else vanishes but the tooltip). If I move the mouse away, then towards again, the window comes back. But because of this weird problem I can only see one window at a time. It wasn’t doing this in the first twenty seconds or so, but started when I tried to enter edit mode for the default cube.

Beyond that, 2.54 works fine. I have Python 3.1 installed, but it apparently doesn’t care either way. But if I can’t see more than one window at once, I don’t think I can work productively.

EDIT: Now it froze, and then crashed after giving me a repeated “Image too small” message. Something is amiss.