I'll give disconnecting the battery a try and see if I can clear it. I find it a little strange that the light will not go off at all using PA Soft. I figured it would probably go off for a minute and come right back at the least.
As for history I've owned the car for 6 years, bought it with 45k miles and as far as I know the airbags were not deployed in the 45k miles before I owned it. The light has been on for probably a couple of months now, but before that I've never had it come on. Nothing obvious happened to cause it, just popped on one day. As far as I know the control module is original.