Strange PDC problem.
 

Today I was backing out of the garage and I noticed the PDC didn't pick up the garage wall, like it usually does.. A split second later, the warning tone came on full, to tell me I was within 12" or whatever it is of an object.. I wasnt. I looked at the sensors and they were a little dirty so I wiped them off. The problem continued in my driveway, and every time I backed up for the next three hours.. Then it suddenly started working normally again. It was very weird.

Also, I was on the highway and I had my headlights on. The dimmer switch for the instrument panel was as bright as it would go. At one point I looked at my radio and I could barely see the time on the display.. Then I noticed all the panel lights were dim. A second later, they came on again.

Anyone know what could be causing these problems?