It might be your browser. I use firefox and it's the best all around browser in my opinion. Plus it's free so you might as well try it out.
If the new browser doesn't fix it then you have a problem with your computer. When it freezes is it completely unresponsive? Or can you still move the mouse or if you hit the power button it will snooze? If it is unresponsive you need to bring it back and have it fixed. You also may have spyware, i had this problem. What antivirus are you using?