2002 Saab 9-3 repair Question Not sure what the problem is

Hi! Do I have a question for you. My local mechanic is stumped. Occasionally when I start my car, and it starts fine. The alarm lights go off but Within 60 seconds all of the alarm lights come on again. the ABS, the Traction control. If I turn off the igition and restart the car they all go off. This may happen 4 consecutive times or it might happen 4 times out of 60 starts. Additionally, now the thermostat needle sometimes drops to the lowest point but if I turn the car off and restart it comes back to normal. I don't know if this is an electrical problem, a sensor gone bad or what? Any ideas?