I have been trying to use the Visual Style Builder for the last 2 days to no avail. I build a new skin called "TEST", select Grid, and base it on the "Vista" skin. Any changes I make using the Colorize functionality works as expected, and saves the skin fine. The downloaded file works in any projects I use it in. However, if I try to fine tune the skin any changes I make cannot be saved. I get a pop up message that says (also see attached screenshot):
"Skin Update Failed! A server error has occurred. We have been notified and will try to resolve it ASAP. Sorry for the inconvenience."
I have reproduced this on the most recent versions of Firefox, Chrome, Safari, and IE9. BTW, IE9 doesn't give me the option to remove images or indicate that any are being used.
Since I hadn't seen a post on this, I figured I'd mention it...