Both me and Pyrorex have tried this with the same results.

When the maximum possible resolution is chosen but fullscreen is not selected, it crashes on startup, with the error message:

Manually setting the fullscreen option in Settings.ini or setting the game to fullscreen before restarting with the new resolution works just fine.

Could it be because we're running less common aspect ratios?
(5:4/1280x1024 for him, 16:10/1440x900 for me)
Has anyone run into this with a 4:3 resolution?

I'm assuming the game is trying to draw its window content that large and then add the standard window border, which exceeds the screen resolution and causes the problem?

Are you running window'd above your desktop resolution, I wouldn't want to be doing that anyway.

Mine's a pretty common aspect ratio, the maximum was 1280x1024 for me. Fairly common res.

No, it's running it windowed AT your desktop resolution when it is the max. Same result for me.

I also had it crash with max res in windowed mode.

I'm running 1280 x 720 and I can't get it to work for the life of me.

I've tried setting my desktop to 800x600 as well to no avail.