Demo won't even start

[Mama Luigi]

I did a few searches and didn't find anything, so here's my problem. I heard about TQ and wanted to try it so I downloaded the demo through Steam. When I went to play it, though, it wouldn't even start. I'd instantly get a message saying it stopped working properly and I'd have to quit. Since it's Steam, I know I have the most recent version.

Anyway, I'm on a desktop with a nice video card (Athlon X2 4800+, Radeon HD3850), and my OS is Vista 32-bit. I have plenty of RAM (2 GB) and hard drive space. So it seems like it's a bug rather than a technical limitation of my hardware.

Thanks in advance for any help!