A you don't give ANY details of your computer (PC? Mac? OS? etc?) or what you mean by 'freeze' all one can do is guess.
Assuming a PC with Windows XP SP2? The usual reason one gets problems is lack of memory. Your PC should have at least 512MB RAM. If you don't understand any of this please put on a NEW past with any questions and more information about your computer.
t, June 2007