Red Hat 7.0 / freezing problem

Hey, when I am in the Gnome, I sometimes experience freezing. It happens when (say for instance) I am in the control center and I change from one I item to the next.ie(window manager to say to screen saver.) It just could be any combination it seems.
The cursor just stays to the watch icon forever it seems. My Question is this. How do you get out of this condition without having to striking control alt delete.
Is there a way to over-ride this and still stay booted up???
Thanks for your help……Pat