Windows 7: my pc doesn't sleep anymore.

I made no changes, but my PC doesn't sleep anymore. I can leave it for hours, come back and the monitor is still brightly lit and my email is up to date. The turn off display is set at 30 minutes, and Put computer to sleep at 1 hour.

Hello and welcome cpzachar how long has it been like that?

Plus could you tell us what is set in the Control Panel Power options High performance Balanced etc

In addition work through these Sleep Mode Problems - Vista Forums.

The problem is almost always the Display driver. Update it, roll it back, reinstall it.

If all else fails then Gather a Startup, Shutdown, Sleep, Hibernate, or Reboot Trace - Windows 7 Forums

I had this issue before and it just happened again (did a reinstall and cleared the BIOS in the process).
Check your Sleep setting in BIOS. I had to change it to S3 for sleep to work properly.

I found some similar old threads on the forum and changed the Power Saving Options on my PC. The problem has fixed itself although I don't know why. I did not fix my BIOS because I didn't quite understand how to get there. The problem had existed since 11/22, about a week. Thank you for being there.

To look at your BIOS power settings enter BIOS setup by tapping the Key (often F2) given for that on the first boot screen, or in your Manual on the PC/mobo's Support Downloads webpage. Choose S3 if available, save and Exit.

gregrocker: thanks for the link in Vista's forum-it is in great detail of this sleep problem. I tried the driver and Dell updates, but it did not make a difference. This is a sporadic (Windows) problem (as I have read the many complaints of others), that I was able to resolve previously. I checked the BIOS setting for power management as per the VISTA link: powercfg -a , and it showed that I only have S3 support, while S1 and S2 do not have the necessary firmware. The pc was not awoken by anything according to : powercfg -devicequery wake_armed. Is there a fix for this as I have set my power options to all different settings and it still will not sleep, but just shut off the screen?

Is there a newer BIOS update on the PC or mobo's Support Downloads webpage?

I just downloaded all the updates that Dell recommended: BIOS, an Intel Chipset, and video controller. Dell makes the MB so I did not find any other info on that.

Does this solve the problem?

To test it you can set Power Options to Display timeout and Sleep at one minute, then in Advanced options your Balanced Plan set Hybrid Sleep on and Hibernate to 2 minutes. What happens?

Next run Important and Optional Windows Updates after enabling Automatically deliver drivers via Windows Update (Step 3). Are there different drivers that Windows 7 wants?