When I try to start TC or AP nothing happens. Task Manager shows the exe is running and using 116kt of memory and 0% of cpu. I cannot force the exe to stop so the only way to close it is to restart my computer. The strange thing is that the steam versions of AP and TC work just fine. I tried downloading the file again. I am using W7. Also GOG and Steam versions have not been installed at the same time.

Edit: Just closed avast and the game seems to work. Lets see if this is consistent or just a fluke

I have the same issue and also use avast. But I already have removed the gog version so I can't test it for myself right now. That scrambled my ingame key mappings and mod packages. xD The retail version is installed as well (only TC).

I would advise you check whether you use ffdshow or not. If so, a conflict is a distinct possibility.

Now, TC is a weird animal. Whereas all games, including AP, work on my system at max settings, TC will CTD anytime I put vertex shaders other than low and /or AA bove x4. I suspect something between the AMD radeon driver and TC. Well, anyway, it's more than playable, but I spend half a day thrying to find a solution to these crashes...