Drop-down menus intermittant

I am using Responsive Green Theme

I have noticed that when I click on an image that is included in a content using colorbox and then close the image then if I hover over any main menu link, the drop down menu opens but does not close as expected normally. So when I move the mouse on other menu links they all open and remain open. If I refresh the screen ( F5) then it starts to work a gain.
If I select an other theme - I used zero point - then I do not have this problem.
I believe this theme may have a bug.
Any one else having this problem?
Haro.