Starmate 5 Problem

When our last, Sirius radio-installed, car was totaled, we bought a new one that didn't have the radio as part of the package. Because of our disappointment, the salesman was nice enough to have a Starmate 5 thrown in. It was installed with a docking station (if that is what you call it) rather than being in the dash.

It has worked fine until just recently. Over the past couple weeks, it doesn't come on at all when we start the car. Usually, after about 10-15 minutes, it comes on. It appears something needs to be warmed up for the power to reach the unit.

This is a new development. It went through the entire winter without this problem.

Any ideas?