Problem with running Crysis all the sudden? HELP PLEASE!

Ok. I have played through a lot of the game now and it has been running perfect. But for some reason, when there is any ice on screen the framerate drops way down. I dont get it. When I am in the lush jungle, which is moving, it runs fine. But, when I am in the later levels where the island is iced over the game becomes extremely choppy. The ice levels are static, nothing is moving except aliens,so why would the framerate go to crap.

I am running Intel Duo E6700, 8800 GTS SLI, and 2 gigs of ram. Is it because of my hardware, or is it the game?

Also, when my disc drive reads the disc it makes a clicking sound. It doesnt sound good. It also takes longer to read.However, it only makes the noise with this game. My drive doesnt make any bad noises when I start up COD4 and Battlefield. Please help me.

Even though the ice level looks static, there may be more intensive shader effects being applied to give the environment its appearance.

As for the disc clicking - do you have another system/drive to spin it up in to see if the drive is a problem?