Weird Firefox 3 theme problem

[Nevilledog]

I was browsing Mozilla and looking for new themes...I download several and then restarted Firefox so I could look and evaluate them. Well, it started up with a DIFFERENT theme than I had to start with even though I had not changed it...and now the damn thing won't let me install or change to any other themes. In the add on window when I click on the themes button it does not show any themes to choose from and no way to uninstall the current theme. It doesn't list ANY themes. Any idea of what's going on and how I can fix it?