Vista - Computer wont always go into sleep mode

every so often I'll leave my computer on for several hours and come back to it and notice that the screen has turned off but it hasnt gone into sleep mode. this doesnt always happen there are time when my computer will sleep when its suppose to but I just cant figure out why it doesnt always do it. I have my screen saver to come on after 10 minutes the screen to shut off after 30 and its set to go into sleep mode in an hour but like last night when I went to sleep with my computer on and woke up hours later only the screen was off. does anyone know the cause of this?

Penfan

We could help you a lot more if you would fill in your system spec (lower left corner) so that we know what kind of hardware you have. also 32 or 64bit?

thanks
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Ken

Well I have a dell inspiron 1525 with vista 32 bit with 4 gb of ram with a intel pentium dual processor

I wonder if there is some application that is actively running to prevent sleep mode?

Hello Penfan,

You might check through all of the items listed in this tutorial below to see if it may help to see if something it waking up your computer. A usual cause is the "Allow to wake computer" setting checked in the Network adapter's "Power Management" properties in Device Manager (Control Panel).

Power Options and Sleep Mode Problems

Hope this helps,
Shawn