In our space named "My exprover", it is impossible to click on the top menus to display the submenus
When we are on the home page (https://my-exprover.jiveon.com/activity), it works.
Once in the group, (https://my-exprover.jiveon.com/groups/general) it doesn't work anymore.
We tested on Chrome, Firefox and IE 8.
I just did some brief testing in that group you linked and I am not seeing the issue.
Is this still happening on your side at this time?