When i try to put the sync every frame option off the game crashes, lots of modern warfare 2 tabs open with black screens

wow, thats not normal.

have you tried to reinstall the game (with fresh game files?)

Facehunter.no. Go to your main folder open config_m2.cfg or something with notepad or any text editor search for r_vsync 1 and change it to r_vsync 0 save and start the game