[CentOS] grub problems

This is irritating: I've got a server I just upgraded to 5.4, then
rebooted, only to discover that it just *sits* there at the grub boot
menu. I looked at grub.conf, and uncommented hiddenmenu (which should have
been done long ago).

It *still* sits there when I reboot. Any clues, folks?

         mark

grub.conf:
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.18-164.2.1.el5)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-164.2.1.el5 ro root=LABEL=/ rhgb
        initrd /initrd-2.6.18-164.2.1.el5.img
title CentOS (2.6.18-164.el5)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-164.el5 ro root=LABEL=/ rhgb
        initrd /initrd-2.6.18-164.el5.img
<snip>