I am trying to publish some workbook to the server. I first log in to Tableau server from Desktop. I choose some workbooks to publish and do some editing for what users can and cant. Then I press "Publish" --- all is going along fine. Then "Tableau Server Sign In" pops up. Fair enough, maybe a bit overkill since I already logged in. However, the exact same user now T Server tells me is invalid login. Something very strange is going on. I have been trying over and over again. I shut down. Start everything up. Same thing happens, but once in a while it does not happen, and publishing is all good. Any suggestions? I am using Tableau Desktop 8.1.