No Return to Sleep Mode

In 'normal' use my computer will go into sleep mode in line with the parameters set to control this function.
However twice a day, sometime in the early hours of the morning and between 14:00 and 15:00 in the afternoon, the computer will awake from sleep mode, presumably to carry out some underlying scheduled task, and then remain awake continously.
Since the computer is driving a large plasma display, which activates as the computer activates, this is an extremely non-green activity.
I have checked the sleep parameters many times but have been unable to find a clue as to how to overcome this situation.
Any ideas?

Coloureng

 

Thanks Arie that was helpful.
The report generated indicated there were 8 errors, 8 messages and some information. Of the errors, 7 were USB related of the form 'USB Suspend: USB Device not Entering Suspend' and 1 of the form 'CPU Utilization: Processor utilization is high'. If these errors are responsible for the non-return to sleep mode following an auto wake-up I would appreciate advice on how to correct them. I am puzzled that in normal operation the system enters sleep mode automatically in line with the parameters set in 'Power Option', yet when the system is woken from some unknown scheduled event this automatic sleep operation does not occur.

 

Sorry but despite searching all the folders in the root I could not find the Event Viewer. Please advise.

 

I knew I would be embarrased!

Very informative but not used.

I went into Power in order to change the sleep timing settings to 5 and 10 minutes respectively for quicker analysis of remedies and the fault I have been living with for months, i.e. the non-return to sleep mode disappeared!

Thanks for you help;

 

Resolved