I just tested this (Sortable Fancybox Gallery 1.15, Fancybox 1.3.1, Concrete5.5.2.1) and did not experience any issues (also, nobody else has reported this issue before).

I suspect it might be a conflict with another addon you have installed or perhaps the theme. But if the upgrade to fancybox 1.3.4 solved the problem that's good to know -- I should probably update that the next time I update the addon anyway.

Thanks for reporting this.

-Jordan

Cool, thanks :-p I spent a while trying to figure out exactly where the error was originating, and I didn't have any luck. Chrome's Inspector just listed jquery.js as the point of origin, and I knew that wasn't right.

Yes, it can be very difficult to track down javascript errors due to the large number of js files being loaded at different times and via different methods (some loaded by js themselves after the page has loaded, etc.).

I usually find that inserting "debugger;" statements into the code is the only way to see what's happening in the inspector.