Problems with adding Pages/Anything to Menu

Hello,
I usually try working out my problems myself and avoid posting here but this time I seem to have reached a dead end and would appreciate any help you guys may have to offer.

I am having problems as I try to add a new page to an existing menu in the admin panel. As I click on the ‘add to menu’ button it seems as if it begins loading and processing the action (round icon thingy goes on and on next to the buttn) but nothing happens, the loading just persists and doesn’t do anything. On a possibly related note, I experienced similar issues before trying to update widgets (those issues eventually resolved on their own, so I paid no mind to them)

I’m using the PageLines Lite theme as my parent theme and have tried changing themes to the Twenty-Eleven theme to make sure this isn’t a theme problem but the problem persist. I attempted re-installing WP and still a no go.

Any advice or thoughts on what may be causing this ?

Thanks in advance.