What did you find at the dealership? My car started doing this yesterday. It does not lock when pulled into gear and I can hear a clicking sound in the gear shift area.

 

to the forum madred!

I moved this post into a new thread, one of the problems with tacking a question onto a thread that's 7+ years old is that the OP, in this case bowser625 left the Forum in 2008.

The clicking sound you hear when you depress the brake pedal is the "Brake/Shift Interlock Solenoid" functioning. It's designed to keep the shifter locked in Park until you depress the brake pedal, a safety feature that dates back to the 1980's when Audi 5000's were flying through garage walls when folks got their feet confused and yanked them into Drive with the throttle depressed.

In your case it sounds like a failure in the correlation between the Shift Interlock and the BCM(Body Control Module) which is an electronic module that controls the locks etc.

You can try giving your HHR a "Lobotomy" as we call it here, disconnect the NEGATIVE battery cable at the battery for 30 minutes to reset all the various modules to their factory defaults. Then reconnect the battery and see if the problem persists, if it's still not properly engaging the Auto-Lock function, I'd suspect a failure in the shifter or the need to have the vehicle checked by a technician using a Tech II Scan Tool to see if the BCM is seeing a request to engage the locks.

Another point worth mentioning, your battery might be starting to fail, as HHR's are known to go slightly "nuts" with low battery voltage. So having an auto parts store check the battery is not a bad idea, since an "undervolt" condition will cause problems.

 

Welcome to the site! X2 on the battery lobotomy, try that first, as it's free to do!
Then get to your local parts palace and have the battery checked and your alternator, charging system