Thanks for your response.
I originally upgraded the agent, but have since manually uninstalled it, rebooted and reinstalled. Still no success. I have also tried a test pool without ThinApps as you suggested, but even though it seems to result in fewer crashes, the service still crashes on most of the log on attempts.
I have since my original post also tried with a new clean Windows 7 image. I have added all the ThinApps to this test pool, and put the vm's in the same OU so the same polices get applied. On this pool the View Persona service does not crash. So there must be something on my original template that causes View Persona 5.3 to crash...