problem with sub menu in some pages

Hello, I have a problem with submenu in some pages. For instance in contact page submenu works fine but in home page sub menu has different settings ( it happens to another webpages also) e.g insead of display:none it has display:block and left:999px.

What does it causes that?

This is my website: exitpolls.gr/neosite/

p.s Some translation for menu

Αρχική = Home page
Επικοινωνία = Contact

Waiting for your replay. Thanks in advance.

I think that I found the problem, in some pages has more than 1 jquery library and that's why it doesn't work right.
I use noconflict to library that I entered but no changes.

Any idea how could I solve it?

I finally disabled js method and I used css method.