Hello BZW,
SYMPTOMS
You cannot change desktop themes, and you cannot select the Windows XP theme on a
Microsoft Windows XP-based computer.
CAUSE
This problem occurs when the Themes service is stopped.
To resolve this problem, start the Themes service. To do this, follow these steps:
1. Click Start, click Run, type services.msc, and then click OK.
2. In the list of services, right-click Themes, and then click Properties.
3. On the General tab, click Automatic in the Startup type list.
4. On the General tab, click Start under Service status, and then click OK.
5. Exit Services.
information from
http://support.microsoft.com/default...b;en-us;883391
See if that helps