Get the CSS on this site to validate. Wierd thing is it was mostly the gallery plugin FAlbum. It used a file called csshover.htc and apparantly this isn’t valid.
When it’s put through the validator it says that the property behavior doesn’t exist. So for now it’s commented out along with a few other bits ‘n bobs that also don’t exist. If anyone has a clue about the above let me know. What the csshover.htc file does is add a grey box around the picture you’re currently looking at, I think (basically I had a look at the plugin site and that’s the only thing my gallery doesn’t do that it does). For now though, everything still works and looks the same and so to be honest I’m not too worried as I like it as it is anyway, it’s just a bit odd :)
edit: It seems the behavior property is a proposed addition to CSS and is not yet valid. So, if anyone else knows how to get this added into my site and it still be valid, let me know!