Guild Wars 2

This just started happening to me today out of the blue. Oddly last night was just fine in windowed mode, went to bed (leave computer running), no updates, didn’t install any new drivers, so as far as I know nothing changed.
I actually logged in a few times to check mail and TP stuff, everything was working fine, logged out to get some work done then this started occurring to me:
– Start the launcher
– It checks for updates
– Login
– Click the ‘Play’ button
– The game window shows for a split second then vanishes

Any attempt to click on the icon in the task bar didn’t show the game. Shutting everything down, rebooting the PC, and running just the game didn’t resolve the issue.
I didn’t know about the <right click>/maximize option, so deleted the GW2.dat and re-installing the game, which will default it to full screen, so I am guessing I will be fine after the download.

I am on Win7 HomePro 64bit, running NVIDIA GeForce GTX 770 with the latest drivers, duel monitors.

I really don’t want to run full screen so hopefully there is an answer.