Hero Academy Steam Version - White S ...

As per the subject line, I can run HA through Steam, and I get sound, but the window is white. If I click blindly I can get the little selection noises, and the button that pulls up the tutorial youtube video in your browser works.
 
I'm running Vista on a Toshiba Satellite A135, I have Service Pack 2 installed, which includes DirectX 10.1. My Intel HD video card drivers are all up to date. I've verified the game cache, I don't have Zonealarm installed, I've uninstalled Steam and HA and reinstalled them. I've run out of things to try to get this to work, and I don't have another PC on which I can install it- I just want to log in with my HA account so I can use TF2 on my phone.
 
Has anybody else had this problem? Is there anything else I can try to fix it?