Cant play cod4 online

when ever i start call of duty 4 and click on join game the screen freezes and i go back to the desktop with a little window saying the application has quit unexpectaly and then i get a report which says
Exception Type: EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000000000000
Crashed Thread: 0
and then loads of letters and numbers. im fairly new to mac so dont know much ive tried reinstalling the game as well but that didnt help

 

no its the mac version of cod4 whats crossover btw