Migrating from J1.7 to J2.5 and JS problems

Hi, I have a problem with support for modal pop-up to the cart. J1.7 to J2.5 was updating, and VM to newest. I can not leave to deal with the problem of pop-ups, and Javascript. The console shows errors:

Uncaught ReferenceError: SmoothScroll is not defined gk.scripts.js:3
Uncaught TypeError: Cannot read property 'msie' of undefined /components/com_virtuemart/assets/js/fancybox/jquery.fancybox-1.3.4.pack.js:18
Uncaught ReferenceError: Tips is not defined (index):1135
Uncaught TypeError: undefined is not a function k2.js:175
event.returnValue is deprecated. Please use the standard event.preventDefault() instead.
Uncaught ReferenceError: $Gavick is not defined engine.js:14

Or get information about looping scripts in gk.script.js. Already was copying files from a new package downloaded from the site. I tried to replace multiple single JS files, but nothing helps.

I wonder if removing mootools.js and transition to jQuery would not be the best option in this situation. But I'm not sure if this is possible in 100%?

Link to this page send to PM.


sorry for my english

sorry for post under post

Below is the list of errors for JS

XHR finished loading: POST "http://site.pl/index.php?lang=en&tmpl=cart". mootools-core.js:474
Uncaught NotFoundError: Failed to execute 'removeChild' on 'Node': The node to be removed is not a child of this node. mootools-core.js:109
4
Uncaught TypeError: Cannot read property 'getElement' of null gk.scripts.js:207