2000 Grand Prix - Window and radio don't work

I have a 2000 Pontiac Grand Prix SE with the 3.8. Although I'm not sure if it has anything to do with the problem, it all started when I disconected the batery to do some work on the car, although not electrical. After conecting everything again, I took the car for a test drive with no problems. The next day, the radio wouldn't turn off as it used to when the key was removed and the door opened. The only way to turn it off was to turn it off at the radio itself. I figured "old car, oh well". The next day The radio wouldn't turn on, and the display where the time and station are shown was dark. All other lights on the stereo still worked but it won't play CD's and the radio won't play either, in addition to that, all four power windows stopped working, at first I thought it might be a fuse, but the two systems seem like odd ones to put on the same circut, and in addtion, the preset lights, volume lights and all other lights on the radio, save for the LED dispay still work.

Anyone else have a similar problem? What was the fix? I'm not taking a 10 year old car with 120,000 miles to a dealer so they can charge me who knows how much to fix it, I just can't see the sense in that...

Any help or advice would be greatly appreciated.

It sounds like you have a problem with retained accessory power aka RAP. Check the operation of the RAP relay which is controlled by the body control module (BCM).