[Sugarnutz]

"unable to find interface attached to first HD card" sounds like the interface is bad or the cable to that interface has went south. I’d check those as this doesn’t sound like it’s your HD cards. If you have more than one interface/cable it should be easy to do.

First disconnect all interfaces/cable and start with just one interface plugged into your core card, if it doesn’t work swap cables.
If it still doesn’t work swap interfaces.
After that and it still doesn’t work I’d try a reinstall of Pro Tools.

Good Luck!