I was able to duplicate the problem and fix it. It was tied to a change I'd made last night. Here I thought the changes had made a huge impact on server workload, but the impact was possibly mostly because people couldn't get to their boards.
What was happening was that if you weren't logged in and tried to do a search on ticker (and this may've also been true of free members), the site was blowing off with the http header error.
I was able to fix it in a way that doesn't dramatically change the changes I made last night, so I should still be able to get a valid test today of the impact of those changes.
None of the changes I made last night affected Premium members, so none of them should've had any problems.
Thank You to all who sent cut/pastes and explanations of what you were doing when it happened.
Market Data 
Markets 
AI
