Trip Computer...
 

Hello,
I recently bought a used 2004 XC70 from a dealer. I love the car, its awesome. But since I am new to Volvo's I don't understand some/most things about it.
Like most people when I fill up the tank I use trip computer to estimate various things(MPG, Trip Dist. Ect.) However, I find the computer resetting itself on its own. Usually it will reset once I am over 100 or so miles. However, it is pretty much at the random will of the car.
I was wondering if anyone could offer a suggestion as to what is going on with car, that would be great. Thanks!