Happened to me yesterday after I upgraded to the new build. Turned out my starting the program from the toolbar shortcut icon instead of the desktop icon was the problem. The new build didn't update the target for the toolbar icon. I clicked the desktop icon, and all was copasetic. HTH
new build 819 would not log on since I upgraded , so I have been using browser based. Today rolled back to 818 and works fine!
There are new jar files in 819. You need to update the startup string in the start menu (and all other places) to reflect the string of the TWS icon that the install program placed on your desktop. See this thread for details http://www.elitetrader.com/vb/showthread.php?s=&threadid=29776 The upgrade to 819 would be a good place to do a clean install.
I've read on the IB Bulletin board (Freelance Tools) that there are also autologon problems with a product called "twsstart" (which apparently automates several TWS processes, including logon and API connectivity) after upgrading to TWS Build 819. Its author has posted an updated version for his product at http://perso.wanadoo.fr/beejay/tmp/twsstart2/TWSStart_2.zip although from what I've read some people found this fixed the issue while others did not. Something significant definitely changed with TWS build 819. This seems to square with what PuffyGums has pointed out with its startup procedure.
I never upgrade to newest release until after about a week at least. Specifically for this reason. Jay
The start up string that the TWS install places on your desktop icon is correct, but you have to make sure that the icon, start menu item or autologon program that you actually use to start TWS also reflects the new startup string.