Logged in and saw I had 17 new private messages. When I checked my inbox it said my inbox was too full to display the PMs so I deleted my messages. When I was at 12% one PM was added to my inbox but emptying my inbox no new PMs displayed. I cleared my sentbox and checked to make sure my outbox was empty too.
I would have PMed a mod but I was afraid I wouldn't get their message.
What browser are you using? Firefox. Tried Chrome and saw the same thing.