I am having the exact same problem!! I just invested in a new imac because I thought the problem was partially because of a 7 year old computer. Even with a brand new install of Photoshop and Illustrator, the programs will not let me open existing files (because of a "program error") or open anything outside PLof the programs (like presets that I recently purchased) without shutting down. They just close the window and go back to the program screen... Forget about assigning the created files to their proper folder, I am lucky if I can get them to save anywhere before the save screen closes. This is extremely frustrating and is making me add quite a bit of time on each job.
PLEASE send help!!