Preventing execution of new modules?

Hello. #C++ failed me.
How would I got about preventing execution of code in new modules (injected DLLs, etc.)?

Thanks.

The point I am making is, it is pointless effort to try to preventing cheating. Trying make more harm that good. You will still be cheated on. Not counting things that are potentially impossible to prevent, like spawn killing and excessive team killing. You can try but will always also hit innocent players.

Here a good reading:

http://www.twistedmatrix.com/users/glyph/rant/softethics.html