Comment 3 for bug 706251

Addendum to the above posting. To change the Power management settings, you have to login to System Settings as root:
<ALT+F2> kdesudo systemsettings
go to Startup and Shutdown --> Service Manager. Check that the Power Management option in the Startup Services pane ( bottom half of the screen) is running. If it isn't highlight it and click the button "Start" int he bottom right corner.
Go to Power Management, --> Power Profiles. Make sure "Dim Display" and "Screen Energy Saving" are checked. Set the times for each int he text boxes; making sure that the Dim Display timing is less than the Screen Energy saving time. eg: Dim Display set for 10 minutes; Screen Energy saving set for 11 minutes (for example).
Click Apply and exit the SystemSettings box. Do not switch off the Power management module that you switched on earlier.
All should be well. Should being the operative word here! :D