Carl,
From your description above it sounds as though you:
1. loaded a live disk into a ProDiscover project
2. extracted an PST to your local disk
3. then loaded the local disk (c: drive) into a project
4. then loaded the PST into the PD email viewer conducted a search which caused PD to crash.
Is that correct? If so, can you try to extract the PST to an external drive and then load the external drive into your project and try your search again. I will attempt to recreate the crash in our labs and update you as soon as i know more.