Unable to load/install desktop theme

I have Dell Dimension 4100 computer with Windows XP Home, SP1, with MS Plus! installed. Browser: Firefox 1.0

I was trying to install a certain desktop theme from http://www.taterbugsplace.com, when I get this error:

"The theme could not load because one of the needed theme files could not be found. This can happen with themes that are not installed or not authored correctly. You should verify that the wallpaper, screensaver, icons, sounds, and other files are in the correct location."

I contacted the creator of that theme, and thinking that I might have downloaded a corrupted file, she emailed me her original file. And I still had the same error, even with the original file. I know that theme from inside out and am aware that ALL the components for this file are accounted for. I'm sure there is NOTHING missing in this file. But the error message indicated otherwise.

Am I missing something? If so, what do I need to do?

thanks,

lmb59