On GuildWars, how do I change the screen resolution using a keyboard? Help.?

Ok, I was playing and I needed to change the screen resolution on my keyboard. Well I did this and when I was done, the screen went black and a box said ';Input Not Supported';.



Now it didn't used to do this before. What happened? By the way I use Windows Vista (No hate comments please.)On GuildWars, how do I change the screen resolution using a keyboard? Help.?
Go to Options under menu. If your screen is F.U.B.A.R. then reinstall the game.On GuildWars, how do I change the screen resolution using a keyboard? Help.?
I think it's f10 or f11 for the options screen...from there, I don't know how to do that part with the keyboard.