I think you just shouldn't be ABing for too long, pretty suspicious when you're on for like 12 hours. If you want it to auto shutoff, you can download an auto shutdown/restart computer program so if you know you're going to be running Abrosia for more than 3+ hours you can schedule it to turn off your computer in 3 hours. Hope that helps.
I actually have this problem right now too. I have premium, but the toolbar is off. I notice when it doesn't buy anything at all for more than 30 minutes and I click stop. It says "Stopping..." when I press stop for more than 2 minutes, so I have to restart the program.