That CLEAN RE-INSTALL may be the issue. Did the person who did that follow Dell's install instructions or did they "Guess?"
Also there are other reasons such as what was plugged in to USB ports or other software. Did you watch for this issue as you plugged stuff in or installed apps?
I have Dell Inspiron 580 Windows 7,SP1.
8gb Ram,500gb HD,Clean re-install 1 month ago.
1st page when I go to screensaver box:wait 10 minutes,resume w/log on page,unchecked.
settings:turn off display-10 min.
put comp. to sleep-30 min.
Screensaver IS picked,but never comes on.waits the 30 min.,and goes to sleep.when I move mouse,comes back where I was(not a problem there),but I would like to use the screensaver,and have that option.By gosh,Ideserve it,LOL.Any help appreciated.Thanks.