Force a specific Theme not coming down via GPO

Hi all,

I have a quite weird problem on my Windows 2008 + Windows 7 only environment.

I am trying to force a specific theme (aero) and therefore configured the following GPO:

user configuration\policies\administrative templates...(ADMX files)...\Control Panel\Personalization\Load a specific Theme

in the Path to theme field I have tried one at a time without success:

%systemroot%\resources\themes\aero.theme
%windir%\resources\themes\aero.theme
c:\windows\resources\themes\aero.theme
%systemroot%\resources\themes\aero

However I still get the Windows Classic theme upon logging in.

I have run gpresults and the GPO is being applied to the end-user

We are currently using a Mandatory profile for end-users, so I am not sure whether this is to blame.

Has anyone got any ideas or come across such a problem???

Comments are appreciated.