My laptop keeps randomly freezing

Hello, as the title says, when I use my laptop it will randomly freeze. I have the gadget that shows me how much of the CPU and the RAM is being used, and I found that it does it randomly, doesn't matter how much of each is being used. It mainly does it when I'm using firefox. Firefox just stops working, and so does everything else, although sometimes msn and a few other programs will some how continue working. It's really annoying, especially when I'm trying to listen to my music and it freezes because then my music kinda cuts out, then continues, cuts out, then continues, repeat. I've cleaned out the cookies, history, and anything else like that using CCleaner. Any suggestions? I have a Intel Pentium T4300 processor, 2.1 GHz Dual core with 4 GB RAM. Any help is appreciated, thank you.

I don't have vista though, I have windows 7. Also, something I just rememberd. When the events listed above occur, I tend to move my mouse in a circle. The cursor goes smoothly then it stops, waits just under a second, then jumps to where it should be. I don't know if that's any valuable information, or if it changes anything, but I just thought I'd add that.