I have Windows 8. I loaded TB onto my laptop and it was working. After restarting, and clicking on TB I got the message that it was already running but not responding. I tried the ctrl+alt+del to access task manager and close the process, but it could not be found in the list of programs, processes, etc. I restarted and tried starting TB again and got the same message that it was running but not responding. It's not running, but it's definitely not responding. I tried to troubleshoot the problem online and the same thing happened with Firefox. I'm borrowing an iPad to post this. Love Microsoft innovation!