Hi having the same issue, my menu has lots of list items and need to be added more, what happening is I can neither delete nor add a menu item, i.e I delete an item or add but when I try to save page goes blank in Firefox, and displays the following error in Chrome The website encountered an error while retrieving https://mysite.com/blog/wp-admin/nav-menus.php. It may be down for maintenance or configured incorrectly.
Theme: Twenty Eleven,
Plugins: all deactivated;
WP version: 3.3.2
I would appreciate any help, sorry for repeat the same question, I could not find answer in the above discussion