Board Thread:Support Requests - Getting Technical/@comment-1224793-20130815204703/@comment-11733175-20130816110721

It means the site has not properly loaded, and is rarely a persistent error. Normally a page refresh will fix the problem.

If you are finding it happen to you frequently/repeatedly I'd advise sending a bug report in via Special:Contact/bug with as much detail of the issue as you have avilable.