Group policy screen saver does not execute on new Vista machines

We use group policies to enable activation of screen saver with password
protection on our desktops and laptops. This policy works well on existing
XP machines and on XP machines upgraded to Vista Business. We recently
acquired a new PC with Vista Business and found it will not launch the screen
saver when time has expired. Path for screen saver is
%systemroot%\system32\logon.scr. Path is correct on XP and new Vista
machine. Would appreciate any suggestions to resolve this issue. Thank you.
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jdr