When starting up a game like e.g. PES 2011, F-secure won't startup the game.
If you disable deepscan it will, but a regular user with less patience will uninstall f secure or ask for a cashbakc.
Perhaps a gamemode button or option (like bitdefender has) would solve the problem?
Could you please test again with the following settings:
DeepGuards advanced process monitoring disabled
If the game works with the above settings, it might very well be related to a copy protection (DRM) or anti-cheating technology used by the game.
Those sometimes do not work with our advanved process monitoring.
If this is the case, please let us know.
my guess: Did you install with or without Parental Control? (switching it off is not the same!)
try uninstalling it from run or commandline:
<F-Secure>\Uninstall\fsuninst.exe" /UninstRegKey:"F-Secure Web Filter"