Crash on resolution change

[Specops]

I can play the game without any issues, but that's only when I play at default resolution of 1024x768, and I have a 1280x1024 monitor. Whenever I try to change the resolution (doesn't matter which resolution), the game freezes. Actually only the graphics lock up, sound still plays normally. When I alt-tab out of the game after that, I see an error window: "A D3D object has a non-zero reference count (meaning things were not properly cleaned up)". If I try to start the game up again after that, the opening video plays normally, but after the video it just crashes again with the same error. If I then validate the game cache, it always finds 4 or 5 corrupt files and redownloads them. Then I can play the game again, but the settings always revert to defaults after validating the cache, so there's no way that I can change the resolution. If I try changing it, the same thing happens all over again.

Any ideas how to fix this? I'm on 64bit Vista and have a Radeon 4850 graphics card. I've already tried updating the drivers from 10.10 to 10.12, just in case, but it didn't help at all.