Pontiac: 2001 Grand Prix "GT" Please help.

Yesterday I pulled into my driveway, and I had the stereo on. Usually when I
turn the ignition key off the stereo stays on until I open the door. But
yesterday the stereo went off, the horn started blowing, and the doors
wouldn't open, this all happened as soon as I turned the key off. I could
only open the doors manually. I tried 3 or 4 times to get things working but
they wouldn't. I let it sit for about 20 minutes, tried it and everything
was ok. I was wondering if this is anything to worry about.

ok, put a brand new batterey in it! the old one just turned 3-4 years
old. this is yur cars way of crying out for help