Do you have Register Mechanic. I'd had some problems - not freezing but when you add, delete etc programs and such on your computer stuff gets left in your registry that messes it up and the computer won't run right. Several people and PW World magazine suggest running a program that will clean up your registry. You can download a trial that will tell you who many registry problems you have but to fix them all you have to buy the progrom - its about $30.
Also I had problems with running a screen saver. If I had to turn it off. They don't play well with other programs anymore.
