Surfer - Like mentioned above, open up the fobs and look to see if any solder joints/connections are loose. When I bought my HHR a couple weeks ago the RKE was intermittently not working. Then I had my GF take the car to work and when she came home she said the remote was no longer working at all. It turned out that the connector for the battery had one of it's joints come undone from the circuit board. The battery was pushing the connector up and at that time it had also swung to one side making it never make contact with the board. I resoldered it and all has been well since.

 

just finished resoldering mine also and now it works fine. looking at the ckt board ,it was the metalprong on the right side of the battery retainer

all is well

 

Funny mine was the left side of that same retainer