HTTP 400 and Project Server 2010

I'm in the middle of a mystery involving the HTTP 400 error, a Sun Reverse Proxy, Certificates, and Project Server 2010. Sound complex? It is. It has lots of moving parts and lots of possibilities. I have been through three intense days of analysis and have come to only a single conclusion. Something is causing HTTP 400 errors to be reported and, once they occur, the session doesn't seem to reset until you close your browser and start over. Next week, I will be attacking network traffic between the reverse proxy and the SharePoint server (IIS) to see if I can arrive at a solution. It is especially frustrating because the error reporting is giving me no clues. I have looked a the logs on all servers and just can't figure out what the problem might be. More later . . .