Electrical problems?

[jdblown03]

I have an 03 cobra and every once in awhile when I start the car it seems like the amps to rear speakers aren't turning on because sometimes I will have bass and other times none. Today I started the car and the same thing happenened but the ABS light stayed on and battery light. I restarted a couple of times and the same thing, finally the dash lights dimmed and car stalled. Started again and no problems. The car only has 7000 miles and already had to replace alternator 2 months ago and battery last month. Any ideas or problem any one else has had??