lights problem

1997 nissan maxima se, 3.0L v6. 185k miles. As of today whenever i use any electronics in my car the headlights and interor lights dim dramatically. this includes using my stereo, on/off headlights, using my blinker, brakes, windows, ect. but only for a short period of time then returns to normal even if i am still applying the brakes of using my blinker although it dims for the duration if i am rolling up my windows. it even does it under acceleration . if im parked and use, say, my high beams and roll up the windows at the same time my lights really dim, my gauges freak out and my abs light and my airbag light come on but i have not noticed the battery light come on (though it may have). i had the battery and starter replaced last november (2006) and the alternator rebuilt last july (2006) i am totally freaking out that it could be someting really major. this just started today 07-05-07. i should also mention i had an aftermarket soundsystem, head unit and subs/amp, profesionally installed last january (2007) but has never given me any problems. if you guys could help me out i would be very gratefull.

KJD