Is this someting VMware related? CentOS 4 related? Or possibly some misconfiguration on my part? This box has been working fine for months (and has been rebooted many times), so I'm not sure what "changed" (certainly nothing on the host OS level).
VMWare does this whenever you get a new kernel running. It has to have a module that matches so anytime you update the kernel, you have re-run the config script to get a matching module compiled.