Problems with cache

I have the latest version of the Musicity template, 2.5.1. And I have enabled both Gavick cache plugins and the cache seems to work fine. But sometimes when I go to my webiste it looks like no CSS is working and on the top of the page it says "Internet Explorer 6 doesn´t support this webpage..." but I am using IE9 and I get the same message in Firefox 9 and Google Chrome 16 to.

When I clear the site cache the problem goes away just to reapear a few moments later. There seems to be som strange problem with the cache.

Here is my site: http://www.fotoforalla.se/

And here is a screenshot of how it looks when the problem apears:

Capture.JPG

This is caused by your server, please look at firebug and you will see that most part of CSS files is not loaded.

Ok, and why are there not loaded? I only have this problem when I have gk cache turned on.

(Can´t seem to edit my posts.)

Why are my CSS files not loaded? I only have this problem when gk cache is turned on.