Here's the problem. I played once, and it was fun, then I shut it off for a bit and tried to play it again later. When I start the game the mini-start screen shows itself, then goes away as you'd expect, and then I hear the game music play, but I don't see anything besides my desktop. On the task manager the process DB.exe shows itself as running, but no application is shown as running, and I can't see the game or a tab for it on my desktop. Has this sort of thing happened to anyone else? BTW I'm running Vista if that makes a difference. Thanks in advance.

It sounds like a video error. First make sure your drivers are up to date, and Windows Update hasn't swapped in the crap Microsoft drivers for your correct ones.

You can try this video fix - viewtopic.php?f=13&t=347

You can also try adjusting the resolution or running the game in a windowed mode:
Edit My Documents\Dungeonbowl\config.xml (make a backup first)
Look for the <Video> section
Try changing the resolution to something generic like 1280x1024
Try setting Fullscreen to 0 (windowed mode)