I know, but that's of little help. I used that firefox html validator add-on and look what it said:

http://learn-croatian.com/svasta/skrin.jpg

So I'm guessing that those & in the links are causing the problem to w3c's validator. However, if that was the case I don't know how anyone would be able to validate their sites...

And remember, everything is fine in IE and Opera.

P.S. I've changed all & to & but the problem wasn't fixed. There was also the copyright sign at the beginning of the file because of which you couldn't validate the page. I've removed this and it's now possible to do so. Try to validate it again please, maybe this time you'll find more info.