What do you get when you run the following (you may need to run this as root).
rpm -q -a | grep gcc
It sounds like your compiler package is earlier than the one RedHat used to compile your kernel. I would look for an updated compiler package. It might be easiest to check your installation CD's. You'll probably want to check the following directory(assuming /mnt/cdrom as the mount point for your CD drive):
Under this directory (on each CD until you find something), I'd do an
What do you come up with here?