I just bought a 2002 Pontiac Sunfire SE Coupe. It needed a new battery, which became apparent after about 2 weeks of owning it and having cold weather cranking problems. When I first picked it up, I noticed that the clock always displayed "12:00" upon starting. I figured that it was non-functional somehow, so I just kept programming in the correct time when I felt the need to.
After I replaced the battery, the clock displayed the correct time upon starting, until this morning, when I noticed the "12:00" once again. Does anyone have a clue as to what might possibly be causing this?
This vehicle does not have the Monsoon audio system.

Sounds like you might have some sort of drain while the engine is off.