No, nothing to do with the theme. One thing I've found is that there are a lot of places out there offering code for buttons and such with mistakes in them or that are written for HTML, but not for XHTML.
Since I have no idea if you are coding everything yourself, or if you are copying and pasting from other places, all I can do is look through your code give you an idea of the errors I'm seeing.
With the image link code missing the ending space and slash (/) before the ending > - since it is in nearly every image link on your blog - I suspect that is something that is happening when you write the code. Also since I'm seeing a high number of places where single quote marks are used where there should be double quote marks (or single quote marks on one end and double on the other), again I can only assume the code is being written that way.