Computer won't go to sleep

After I restart my computer, the sleep function works fine. But after a certain length of time (8-12 hours?) or a certain number of sleeps (2-3), the computer stops going to sleep. This problem started recently, when I had to have my hard drive replaced due to the USPS' bad shipping. It didn't start immediately, however, it only began after a few weeks or a month.

When I try to make it go to sleep, either via the power button (when set to sleep), the sleep button in the start menu, or the sleep key on my keyboard, the screen does the fade to black after 0-2 seconds. Then, after 3-5 seconds of black screen, the screen just turns back on again.

I have tried setting my network card, mouse, and keyboard to not wake up the computer, I have tried disabling sleep timers, I have tried hibernating instead of sleeping (which has the same effect). I have tried closing unnecessary processes such as autoupdaters in the task manager. I have tried scanning for viruses with AVG. powercfg -lastwake doesn't show anything (probably because the computer doesn't go to sleep in the first place, even for a second) The only thing that works is restarting the computer, which is only a temporary solution. Any help please?

control panel [power uption ] from there you could set your computer to go to sleep when you like to .
really easy to do

yvesj said:

control panel [power uption ] from there you could set your computer to go to sleep when you like to .
really easy to do

Did you even read my problem? My computer won't go to sleep AT ALL. I don't care about autosleeping. In fact, I have it set to never autosleep, and always have.

We see nothing but problems here with AVG so it could be the problem. I'd uninstall it, use the AVG uninstaller | Download tools and utilities then reboot and install recommended freeware Microsoft Security Essentials.

Otherwise sleep issues often concern the Display driver. Update yours from the PC or device's Support Downloads webpage, or roll back to the last installed one.

Other Sleep Mode Problems - Vista Forums.

Check the Performance and Admin logs to resolve repeat errors and check for errors at sleep attempt time, establish a Clean Boot, work through the other Troubleshooting Steps for Windows 7

If you have a System Restore point from before it stopped sleeping, try that as well. Once you fix it keep a Restore Point and backup image labeled "Sleeps."

If nothing else helps you can determine the cause with certainty by Gathering a Startup, Shutdown, Sleep, Hibernate, or Reboot Trace - Windows 7 Forums

Finally figured out the problem (the error isn't that reliable since it takes a while after the restart to show up), and in the admin logs it has been revealed to be volmgr event ID 45 : the system can't load the crash dump driver. I'll try to fix it tomorrow.