Help with Vista machine not sleeping

Hello everyone,

I have a Dell E1505 running Vista Home Premium. I have 2GB Ram, 100GB 7200rpm HD, Dell 1500 Draft-N mini wireless card, and an Intel Core 2 Duo 2GHz processor. I have the latest (A17) BIOS installed, all of the most recent drivers I can find from Dell, and do not use an external mouse/keyboard/monitor.

Here is the issue: the machine will not go to sleep per the time set in Power Management in Vista. When I first got the machine everything worked fine. I moved everything over from my XP machine, installed all the programs, and I had a great computer. Then, a month or two later, it started this sleep problem. It would sleep if I shut the lid, hit the physical power button, or hit power in the Start menu, but would not sleep per the time set in Power Management.

Dell could not help me, I couldn't find the answer on the net, so I backed up the system, used the Dell Recovery Partition, and formatted the hard drive to factory condition. To my chagrin, the sleep problem was still there. At this point I reinstalled everything figuring that I'll never figure this out. Well, about a week or so after that the problem disappeared. I have no idea what I did, but I didn't care.

Well, guess what? About 3 months later the problem is back again. This is the strange part: if I set in Power Management the monitor off time for 1 minute then the sleep time for 2 minutes the computer will go to sleep at 2 minutes. If I set the sleep time for 3 minutes or higher, the computer will not sleep at all on its own.

This is very, very frustrating. I've seen other users with this problem as well. I don't like the idea of leaving my computer to run a task at night and find that the machine is still running in the morning. Please, if you have the same problem post here so we can bounce ideas off of each other...or if you can think of any possible solutions I'm all ears. Thanks!

Rich