Avid Pro Audio Community - Playback Engine Setup Problem in PT 7.4.2

Hey guys, I was hoping someone using these forums might have run across a similar problem and has a new idea for me. The problem I'm having is that whenever you enter the Playback Engine Setup, we only have four choices for Host Engine (see attached image). The system I'm working on is running on a 2 month old Mac Pro (see attached image). We are running a HD5 system, with all the cards in a Digi expansion chassis. Digi test has verified that all the hardware is functioning correctly. I've trashed the preferences, repaired disc permissions, rebuilt the directory, made certain it wasn't a session specific problem, and am at a loss for further ideas at the moment. I'm hoping to avoid re-installing Pro Tools. Has anyone had a similar experience?

Thanks in advance guys.