This may not fix your issue, but it is something to be aware of. When you first load PT8, after entering your registration information, PT will attempt to send/receive every project that you have permissions on. If you have a slow connection or many projects, this could take a long time or even cause you problems. If you click anything else, that send/receive progress bar will often become hidden, so it will appear that nothing is happening, but you can Alt+Tab to see the progress bar again. It is worth checking to see if something like that is happening.
Where we work, we often prefer to cancel this initial send/receive, have the program load up, and then send/receive the projects one at a time.