I have an iMac g4 800mhz. I bought it when they first came out. Up until now, I've really had no problems. However, now the machine won't sleep by itself. It dims, then goes black, but the fan and HD( i think) just keep spinning away. If I manually sleep it, then no problem. Any help here would be greatly appreciated. I love my mac and I love it even more when it's working properly.