I decided to try my hand at creating a theme. I filled out all of the forms, uploaded the images (that were the appropriate sizes), selected the colors, was happy with the preview and clicked 'Submit'. The following screen said, "Oops! You are trying to do something that you are not allowed to do." I clicked the back button and re-tried, then received the error message that the theme name was already taken. I re-named it, re-submitted and went back to the 'oops' screen. This cycle repeated no less than 20 times. I tried theme names that were so off the wall, there's no way that all of them were taken. I think that it was failing due to whatever error it was encountering.