I am having he same problem, and I tried both suggestions. Neither worked. I was told that the upgrade does not apply to my computer, and the clean boot only resulted in my computer booting faster.

Still no screensaver and power save mode. It won't turn off the display, and will not go to sleep.

Btw, I have a Dell Inspiron 1501, and this problem did not start till two days ago. This is just one more of a string of problems that I have had with this thing, and Dell has ot offered me any solutions other than to give them more money. Seriously, do NOT get a Dell. I am sorry that I did. :mad::mad::mad: