Mouse sensitivity is set to zero on game startup
I've managed to solve this problem on my own.

Warsow has a built-in "hack" to disable Mac OS X mouse accelleration, which is on by default. This is redundant to using my "Automatic Kill Mouse Accell" script on startup and causes this problem.

solution:

Open Finder and navigate to your user folder /Library/Application Support/Warsow-1.0/basewsw/ and open the config.cfg file. Search for 
seta in_disablemacosxmouseaccel "1" and replace it with 
seta in_disablemacosxmouseaccel "0".

source: http://www.warsow.net/forum/thread/t/216237#post-216237