There could also be other problems but:
is corrupt. Easiest way to test if this is the only problem would be to replace:
I see the page is also using MooTools (for the visual slider thingy). You may have to put jQuery into noConflict mode to have it and the MooTools library both available. Combining jQuery and MooTools on the same page can be tricky sometimes and sometimes impossible, often it's fairly easy.
And if that's the jQuery Lightbox I'm familiar with, jQuery Slimbox2 would be a better choice - And there is a version of Slimbox that uses MooTools (but I'm not sure which version of MooTools it might require). If you used that and it worked, you wouldn't even need jQuery unless it's also use by something else on the page (the menu?).
If this is the menu:
It's also corrupt. Both of the corrupt scripts look like they may be compressed via gzip or similar but that the browser isn't being told that. So, as I say, there could also be other problems.
Another way this could be approached is that there are jQury scripts similar to the visual slider thing. If you used one of those for that, you should be able to get rid of MooTools.
As I say though, the two probably can work together.
But whatever you do, the corrupt scripts need to be fixed.