We have around 185+ items which includes parent and sub menu items for the MAIN NAV. We are on wordpress 3.3.1 . Everytime we want to add a new menu, we are unable to do it. When we add it and click on SAVE, the page processes for like 5-7 minutes and then shows 500 Internal server error and the new menu never gets added. What wrong with wordpress ? Its so frustrating.
Have you recently added new plugins or functions on your theme? Try to disable your plugins or try using the twentyeleven theme while doing the process.