Dell Dimension running Vista won't come out of sleep mode

I bought Dell Dimension E521 desktop that came pre-installed with Windows Vista. Yesterday evening I was scanning with Spybot that was scheduled to run for more than 10 minutes and I have set my system to go in sleep mode after 10 minutes if kept ideal. Now the problem raised is that while scanning the Spybot, after 10 minutes, my monitor or system went in sleep mode though the scan was running. I tried pressing keyboard buttons, tried moving mouse but my system is not coming up from sleep mode.

I don’t have any idea what this problem occurred all of a sudden. My system was working great since past 6 months. The only new thing happen today is when I started computer today morning I got a prompt asking permission for startup
programs to have access. Any help please ?

I thought its just me alone but seems like there are other people too facing this problem. Even my problem is very similar, my vista is not awaking from sleep mode. The problem started when I started using Logitech diNovo Edge Bluetooth keyboard. I accidentally hit the power button available on the keyboard that makes my computer go into sleep mode. And since then it is in sleep mode.

Please check the lights on your cabinet. I have been through this problem earlier and in my case I was having 3 and 4 lights on my Dell XPS 410. I checked in the manuals about this and found that Memory modules are detected, but a memory failure has occurred..

So I’ll suggest you to check the lights and manuals, see first what the is the problem they have mentioned according to that.

Did you tried pressing Ctrl +Del + Alt ? Try it out. Many times when my monitor goes black I use to get it back by doing the same. Also as far as I know this is the only way we can awake our system without shutting down or restarting the pc.