Guild Wars 2

After the update from some days ago the background of “New event nearby” sentence (which appears in the middle of the screen) is no more transparent. Now it is black.
Same thing happened to the background of the buff given from Sigil of Bloodlust. The buff icon which says how many stack you have now has a black background, no more transparent.

Today I logged in and the problem seems solved. I don’t know if it is thanks to update or what.

After today’s update it happened again. Problem not solved.

I found the cause (maybe).
In the Nvidia control panel 3D settings, there is an option called “Antialiasing – Transparency”. Yesterday I choosed “Multisample” and today I got the problem.
I closed the game, setted it back to “Supersample x8” and the problem disappeared.
So this is a new GW2 bug which forces the user to use highest quality settings.
There is no problem for me but you should fix ASAP bugs like those.