Hi Philip,
I have the same problem.
Just go to the icon on your task bar, right click and hit maximize. the window will then appear. Grab the window by the top and drag to keep hold when it exits fullscreen mode. It will then miniaturize back to basically just a bar. Expand this out to whatever size you want.
This should fix it for the next time it launches, it did for me.
Hope this helps,
Tim