Hey all. Basically, I've been pushing a 22" Hanns G external monitor from my Macbook for months now, using it in both clamshell mode and dual screen. Now suddenly, the resolution on my monitor has completely changed, and whereas I ran it in 1920 x 1200 before, system preferences only shows completely random resolutions, which look terrible. Also, with the new resolutions shown, it is letting me choose what Hz to run it an (60Hz, 75hz etc etc.), which it has never done before now. Is this likely to be an issue with the screen, or my graphics/video card? Any ideas please? I've reset the screen to factory settings, and played about in system preferences to no avail.