Go to support.dell.com flash bios update video drivers.
I purchased a Dell computer this past month with Windows Vista (Premium edition). After about two weeks my screen savers will not come on and my computer (monitor) will not go into the sleep mode. I did not make any changes. The screen just stays on the last site I visited. I have been on the phone (hours) with Dell (bought their 3 year comprehensive warranty - a joke) and tried Microsoft - they wont touch it becasue it was an OEM install by Dell. Seems like it should be an easy fix but I am at a loss. Have tried all the basic stuff to fix. Have contacted McAfee and took off the protection and that did not work either. Any suggestions??