If you can, try switching views or resetting the current view.

If you can't even get that far, you may have to run Outlook with the
/cleanviews switch, which will wipe out any customisations you made to all
your folder views.

This is a pretty general tip when a folder won't display though - I haven't
seen/fixed exactly what you describe with it, so if you have a lot of view
customisations you don't want to lose, you may want to wait and see if
someone else has a more targeted (and less destructive) suggestion...