My monitor only supports one refresh rate (60Hz).
I tried a couple of other resolutions (standard for my PC is 1366x768; I also tried 1360x768 and 1280x720), it made no difference in either fullscreen or windowed mode.
However - switching to 16-bit color mode did make it work in windowed mode (it still didn't work in fullscreen).
In case it's of help, I'm running Windows 7 Home Premium 64-bit, I'm on a laptop with the whole dual GPU setup (though I have the option to choose which one I use for a given app, and the same thing happens either way); the low-power one is simply reported as "Intel HD Graphics Family", the high-power one is NVIDIA GeForce GT 540M. I believe 2GB of video memory on the latter, while the former uses shared system RAM.
Anyway, until the issue is fixed as a whole, seems plugging in another screen (at least on HDMI, haven't tried (and don't have the means to try) doing it on VGA) works as a kludgey fix, so I'll have to jump on and have a game sometime. Is there any real pattern to when people play or anything, or is it just a matter of try your luck with if someone's online at the same time?