I would probably try disabling the opening movie (via the config utility), and regardless if it helps or not, do the file check via the PlayOnline Viewer start screen.

If neither helps, I might play with the windowed mode and resolution options (in the same utility).

I guess it could also be a driver issue of sorts. I haven't used Windows since 2010, but I've seen it have a mind of its own with regards to updates, so the graphics card driver might have changed. The major graphics card vendors there also seem to rather like automagical updates too.

Also make sure no third-party applications related to the game are running around, though I'm not familiar enough with them to know if they could cause this particular issue.

Provided you have the time, a re-install of the game comes to mind, too, though that only allows for the same issue to appear again. :]

If none of this gets you anywhere, it might help if you provided a bit more information about your set-up (operating system, hardware, graphics device driver and such).