This is a very common problem

 

It is very often caused by the graphics driver.  Have you looked for an updated one?

Try unplugging all USB devices

 

In Device Manager check in the properties of mouse and keyboard.  Make sure that "Allow device to wake computer" is not checked

 

Here is a  troubleshooter

http://www.computerperformance.co.uk/vista/vista_hibernate.htm

Also, make sure you have all the latest Windows updates. One or more of them solved my sleep/hibernation problems. And make sure you don't have something running in the background that prevents sleep. If you recently ran Disk Cleanup, you need to read this: http://support.microsoft.com/kb/928897

Hi,

Thanks for your replies.

I have read both suggested documents with great interest but frankly the information contained doesn’t lead me to a solution.

May I had this supplementary information to my original post: I can manually put my computer into sleep mode. However my PC doesn’t automatically go into sleep mode like it used to, i.e. Power Supply shut down.

What can I do to correct this?

Thanks,

Ah, so it used to go to sleep automatically and it can still be done manually

 

Try a System Restore back to when it worked
http://www.howtogeek.com/howto/windows-vista/using-windows-vista-system-restore/

 

Also
Here are various settings to check
http://www.vistax64.com/tutorials/63567-power-options-sleep-mode-problems.html

Hi,

 

I have tried the procedure described at "vistax64.com" and it fixed my problem. I am not sure exactly what setting did the fix, but it now works.

 

Many thanks,

Could you retrace your steps, find the solution (or at least the thread) on Vistax64.com and post a link here? It might help others who have a similar problem.

Okey dokey :smileyhappy: :smileyhappy:

I am glad to have helped you :smileyhappy:

 

 

Rebel9

It is not a thread, but a list of troubleshooting steps to run through

Oops - Sorry. Didn't see the link in your earlier post.

Hi,

As requested, I am sending you the steps I did to solve my problem.

First, I ensure my BIOS power management option was set to S3.

Second, I skipped Step 1 since I could manually put my PC into "sleep mode."

Third, I set my Power Plan Option as described in "Step 2", i.e., Balanced option: Display Off - 5 min., Computer to sleep - 15 min.; Advanced Options: Turn off Hard Disk - 10 min., Wireless Settings - Maximum Performance, Sleep - 15 min., Allow Hybrid Sleep - Off, Hibernate - Never, USB settings - Disable, Power Button - Shut Down, Sleep Button - Sleep, Start Menu Button - Sleep, PCI Express - Maximum Power Savings, Search & Indexing - Maximum Performance, Display Off - 5 min., Adaptive Display - On, Multimedia Settings - Allow the computer to sleep.

Fourth, I executed Step 3 and 4, but nothing obvious or suspicious attracted my attention.

Fifth, I set all my devices to Be Allowed to Turn Off by my PC in Step 5. Notice that the amount and type of device differ from one user/PC to another.

Sixth, I set my Screen Saver to "None" as suggested in Step 6 and skipped step 7, 8 and 9.

That was it.

I hope it can help anybody who experienced the same frustration I had, trying to resolve this problem.

Thank you very much for posting that :smileyhappy:

 

I`m sure it will help people who are searching for a solution to this common problem