Melissa, it sounds like you have an actual internal IPC (instrument panel cluster) issue or one other possibility is a BCM (body control module) concern. The IPC on this car is a slave unit that only displays what it is told to by other modules via serial data (communication) lines. The BCM is, for lack of a better term, the master communications module for the rest of the car. The theft deterrent system logic is also in the BCM which could explain the intermittent no start. I would bet there are codes all over the modules of this car. If any one module on the data line circuit has some type of internal issue, it can actually cause others to malfunction when the fault is present. Nutshell---you need to get the car to a reputable shop with someone who is SHARP with the way these systems function and my guess is it can be diagnosed in 1-2 hours.
ASE & GM certified master technician, and no, I don't think I know it all.