Left front speaker doesn't work with Cd?

[section8joe]

Does anyone else have this problem with the stock head unit. I just bought my explorer(02 xls). While the radio is on the all speaker work. When i put a cd in, the front driver side doesn't work. This doesn't happen all the time I'd say it happens about 75% of the time. I went to the dealership(which im begining to hate) and the replaced the head unit. I'm still getting the same problem. I was wondering if anyone else had this problem?
Thanks
Joe

 

[MONMIX]

it is very odd it would be in the replacement HU as well because it seems like a problem with in the CD mechincism