firefox vs chrome slider behaviour

[franciscaluz]

Hi,
i've tested the slider on these two browsers and though the slider's behaviour is perfect on chrome, it's not the same at all on firefox, where the nav starts off to slide underneath the content of the page and eventually ends up on top like it should...
I don't seem to know where that comes from or if anyone else has had the same issue and maybe how i can fix this?
Thank a bunch

p.s. i'm using the ie version to be cross-browser compatible