If you have old GG files (ijji's AVA or steam's) just replace and it'll work
If you don't; http://www.4shared.com/rar/jXKI9J0M/GameGuard.html?
Mediafire (thanks to heikki): http://www.mediafire.com/?1ke91od664gsk12
Delete the GAMEGUARD folder only at this path:
(If you changed the default installation path:) [your installation path]\Binaries\GameGuard