I was wrong the 500 error went away on my other site. It still exist on the site.
"500 Internal Server Error
The request was not completed. The server met an unexpected condition.
It occures when you try to save the theme. I noticed the theme does not change in the preview window below. The color slider cause it to flash but the screen still has the same color configuration.
It's the same if you do a manual color change or select an image
I'm contacting the server people also. So what happen to fix the first site will happen again.
All permissions are set to 755.