XP Media Center Edition -Tried below but that did not work:
1. Click Start, and then click Run.
2. In the Open box, type regedt32, and then click OK.
3. In the Registry Editor window, locate the following registry key:
HKEY_USERS\.DEFAULT\Control Panel\Desktop
4. In the right pane, double-click ScreenSaveActive.
5. In the Edit String dialog box, type 0 in the Value data box, and then
click OK.
6. Click Exit on the File menu to quit Registry Editor.
The logon screen saver is turned off.
It keeps coming back, even with a power down.