cannot display "all mail items" folder

All my email folders are accessible and I can view email in any of them...
except... the "All Mail Items" search folder. Whenever I click on it a
"Microsoft Office Outlook" pop-up error says "Outlook cannot display this
view." Then, when I close that message, the window where normally the email
panes would show, it says "Cannot display the folder." It had been working
fine and liked using it to locate email using instant search.