First things first, make sure you've got the lates videocard- and soundcard drivers for your system.
You can try to run it in the safe mode option, and see if that helps.
Also, to see if it is because of any conflicts, try turning of everything running in the background, and then running it.
when you say soundcard drivers , i have a soundblaster 24-bit live(2004) but there is a new driver should i download it- how do i get rid of the previous sound driver first? i have upgraded the nvidia driver to 81.94. I have gone back to 'optimal settings' in the menu for COD2--((for my system i was surprised it looked like i had a 1995 computer!)) but it played ok, but graphics arent good 600x800 res with everything turned down, with my system i think this is terrible-- i experimented with screen res but when i went to 1024x768 the game frooze also optimal settings wants to run directX7??)
anyway any ideas? When you say things running in background (not to sure) i know there is about 30 processes running in background but i think i have cancelled the bad ones(answers that work) also what does safe mode actually mean- when the game frooze it asked did i want to restart in safe mode and the graphics at the restart did not jitter in safe mode??