FrameRates lowering in CoD5? why?

[aj95]

i was playing CoD5 earlier and i noticed my FPS was around 20 when i was playing. its normally 30-40. it is affecting my gameplay and its very annoying. i dont know whats wrong. i ended all the "big" tasks that could be slowing me down but still, nothing. any help?
i have Two Sapphire HD 3650's in crossfire. ( i know sux )

 

[Maziar]

Do u have the latest Catalyst driver ?
Does this FPS issue happen in other games too ?