1. Sorry for googleapis, my computer was blocking it... (had some attacks from there)
2. This:
;(function($){
$.fn.slideto = function(options) {
...
should not break a thing ever.
its an amulet-like syntax that will always guard you from unepected js voodoo.
() [parens] can interact in a great distance and some comment might be fooling you that the line break is an established fact, but it might just so happen that an external script at the end of all lines didn't have a line terminator and might have even been omitted knowing that its the end of the file that will terminate not only the line but the script as a whole. But that's not the case -because external scripts will all be appended as if residing in one single and uninterrupted document. So if another js file begins with (... without a leading ; it will be considered a function call of some end-declaration from the previous file.
3. Why don't you try correcting the:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 4.0 Strict//EN">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
into
<!DOCTYPE html>
<html lang="en">
first, -and see what happens...
Anyway, you'll need some patience because this error will not be easy that to locate...;
in jquery-ui.min.js I've noticed an unnecessary line termination in code
...[0].offsetWidth,
height:d[g]...
which depending on the parser - might also cause problems.