Hi Raca,
I don't see the same problem when I install 5.03 on my PC, but there are two ways to solve the problem, the best for you is probably as follows:
Right click on the folding at home icon (the red molecule) in the system tray and select "configure".
Then on the display tab, check the box labeled "Turn on screen saver after x minutes" (e.g. 5 minutes). then also click "Run Core only when screeensaver is active". This way folding at home will not run unless the machine is completely idle for the amount of time you put in the "minutes" field. It may be the game is not being detected by folding at home and causing it not to halt. Let me know what games are causing a problem - I may have the same ones and can give it a try.
You could also click in the advanced tab of the configuration dialog and turn down CPU usage percentage until you find a value that works for you.
Regards,
Al