I installed a RH6.0 system with MD5 passwords. I recently had a power outage and fsck dropped me to sulogin during bootup. Sulogin refused to accept my root password. So, I ripped the hard drive off the server and took it to another linux box and fsck'd the hdd. When I returned the hdd to it's case, I could log in using a regular shell.
This has been fixed in the current SysVinit package.