Hi Adam,
I determined that it had nothing to do with the master page.
I created a new project with a master page and was not getting the error.
Then I noticed that the error was occuring in a Default.aspx page but Default.aspx was not in the url.
When I added Default.aspx to the url the error did not occur.
One other note, the documentation for Installing DotNetGallery step 2 - updating the web.config has CuteWebUI instead of DotNetGallery
Thanks.