[Plugin: NextGEN Scroll Gallery] Sliding doesn't work in Firefox – Multilingual plugin

Hi,
First I’d like to say that I really like the plugin a lot!
But I was having a few issues with it and until today I couldn’t find the cause. Sometimes the sliding of the thumbnails worked, sometimes it didn’t.

I found the cause and it’s a multilingual plugin that I’m using. http://ww.wp.xz.cn/extend/plugins/multilingual-text/

I’m not really into javascript so any help on how to fix this problem (not sure what is causing it since it works fine in IE) will be really appreciated.

You can see the difference by looking at the following pages:
working: http://www.q-cavaliers.com/pictures/
not-working: http://www.q-cavaliers.com/the-q-cavaliers/qwick/

Thank you very much for your answer!

http://ww.wp.xz.cn/extend/plugins/nextgen-scrollgallery/