Forum css not loading after upgrade
 

After I upgraded to 4.0.5 styles started to behave funny. They were not loading properly and the page turned up with no styles like in this screenshot from one of my users.

http://i59.photobucket.com/albums/g3...wPicture-1.jpg

This also happens to me and more of my users. I have now upgraded to 4.0.6, but this is still a problem. It gets fixed when we refresh the page. I happens more now than before I upgraded from 4.0.3

As you can see I have a custom menu, but even after reverting templates it happens.

Thanks