Display Sleep problem fixed,non Apple kernel extensions removed
I run a Late 2009 Mac Pro 8-core 24/7 at about 95-97% cpu use. (2 x E5520 Xeon cpus). After installing OS X 10.7 Lion this morning the Display Sleep function stopped working. Lots of searcing and reading led me to a solution. Credit goes to Bill Ellis for his trouble shooting post http://osxdaily.com/2010/08/03/list-all-third-party-kernel-extensions/
Non Apple kernel extentions were the problem, specifically VirtualBox. Removing VirtualBox solved the problem and my Display now goes to sleep, whew.
Open a Terminal (Finder -> Applicaitons -> Utilities -> Terminal).
Type "kextstat | grep -v com.apple" and see what is there. I then located the VirtualBox folder and clicked on the unistall utility. This removed the kernel extentions (5) and my Display went dark in one minute as I had it set in Preferences -> Energy Saver.
Thanks too the Apple Technical people who listened to my problem on the day that Lion was released. I'm grateful and impressed. Hope that this can help someone else find and solve a problem.
Mac Pro (2009) 8-core, iMac, Mac OS X (10.7), iMac C2D, iPhone 4