While I'm not familiar with "fancyBox" having validation errors CANNOT be helping -- particularly if you have improperly closed tags or markup that violates the structural rules. This is even more true of you start slapping modern scripting and the HTML 5 doctype on what is -- to be brutally frank -- decade out of date markup and development methods.
On the whole (just looking at that first page) you've got all sorts of issues -- from endless pointless scripting inlined in the markup -- IN THE WRONG PLACE at that -- to static screen only style inlined in the markup -- to gibberish use of numbered headings (even by the gibberish HTML 5 changes to the rules), endless pointless classes for nothing, no media targets on your style embeds, attributes that haven't had any business on a website since 1997, comment placements that could trip rendering bugs in FF and IE (yes, I said comments... I know -- crazy... I also said IE so....)
I mean, you've got a 27.5k of markup for 1k of plaintext and a dozen and a half content images -- most likely anywhere from three to four times the code such a simple page should have.
Just the first site you linked to ALONE should be pitched and started over, made to work before you even THINK about worrying about adding scripting to it. That you're having trouble making a script work on top of that mess of invalid error-throwing scripting and invalid markup isn't exactly a surprise.
Particularly on sites that -- again to be frank with you -- I can't see a legitimate reason to even HAVE scripting on; at least not for anything you have them doing so far.