You're right. It's the dynamic-drive chromemenu
I downloaded the current version now.
Ours was still the old one.
And this works now.
But I had to move this code:
    cssdropdown.startchrome(\"chromemenu\")
It was placed at the bottom just before the closing  tag.
I moved it to beginning.
Just after the opening of 
And this is ok now.
Thanks