Odd problem - dropdown menu not working on one page/view

Hi

The account menu dropdown, when in an account, if I click on the "edit profile" button in an account, on the edit profile page, the dropdown account menu does not work - clicking it does not drop the menu.  It is the only page/view this happens on.  I am using a purchased theme, seller of that theme says nothing in theme would stop it.  What could be stopping it please?