[CentOS] Cent OS 6 freezing up

     I've been out of pocket for a while, so don't shoot me, if this has
already been brought up. I'm having a problem with my desktop freezing
up, and I'm running Cent OS 6. It seems to happen while I'm running
firefox. I'm not sure if it's firefox, or the OS that's locking up.
When it freezes up, nothing will respond, so I'm inclined  to think it's
the OS that's freezing up. Has anyone else been having this problem?

Thanks

Jim