Custom Vista Theme won't stick.
 

I have installed my own .theme file and .msstyle into the Windows/Resources/Theme folder. My files exist alone inside this folder yet Vista will often loose my theme and revert back to the default theme. I wonder where this Vista.theme is located? Perhaps I can overwrite it with the same theme I am trying to use in Windows/Resources/Theme folder. This happens when opening the screen saver dialog box for example.

You may have a security program that is reverting the themes back to the default settings. You will need to find this application setting and change it to allow the change in the first place.

More on Vista Themes
 

Since my first post on 5/30 regarding the Themes problem, I was able to restore my default Theme settings by setting up a new user profile with full privileges. This somehow gave the new profile a default theme. This also gave me back my default themes on my profile as well. I then deleted the new profile and everything remained back to normal.

This also corrected another "Theme" problem in which I was not able to save or rename a newly created theme done on Vista using a different desktop background or sounds. The downloaded .theme files really did a number on my original Theme Vista program and my advice is live with the themes that come with the factory settings.

I have Dell Chat Support which is free for 1 year with my Inspiron. Dell could only advise me to pull out the Vista DVD and reinstall it. I'm glad I didn't jump at their suggestion. http://www.syschat.com/images/icons/icon7.gif