MS Access : Navigation pane is suppressed

I received a MS Access form client. It is in access 2007 format. Initially Navigation Pane was not available. Only form was visible. Then I choose options->Current database->checked Display Navigation Pane check box. It is visible now. But It is suppressed and not able to resize or access it as shown in below screenshot. I checked the code by pressing Alt+F11. I could not find script related to navigation pane. Please advise.