I would also run "memtest" off CD #1 for a couple of hours to make certain that memory is working OK, etc.
I rebooted into rescue mode but can't find memtest, only memtest-setup.
No, you boot up *with* CentOS CD #1 in the CD drive. At the "boot:" prompt (where you normally just hit <ENTER> to install CentOS), type:
memtest86<ENTER>
It will run memtest off the CD.
johnn