How to clean Kotor CD Rom?

I got kotor for my pc but it doesnt work good. At first i thought it was my pc but i removed all the stuff on my pc that took up a lot of space. 50% of the memory thing is used. When i play kotor i try to move but sometimes they just stay in the same spot and get in the running position but dont move. And wen it finnally moves there is this one part on the Endar Spire where 2 jedi are fighting. Well wen the xplosion hits the whole combat sequence starts over and never ends. I used gl cleaner on the CD, it worked a little better but not as good. I noe there is something rong with the cd. How do i fix it?