I reset the style.css, but there is the same problem. I also updated to version 1.7, still the same problem.
I just saw that when I login as a contributor and go to another page, the menu colors are working correct. Only the main page stays the same.
I have changed menu item urls to correct locations. Now those correct configured menu items are using the correct colors. Only the items which redirect to the main page are colored red. So the problem is solved
