I have this issue with my Iiyama ProLite B2206WS...
http://imgur.com/a/3W5ZH
In the first picture I just selected the first submenu.
The options inside it look white (usable).
When I ENTER that submenu though (2nd pic), all the options turn grey - I can't do anything.
The same happens in "Image Setup" submenu.
All other submenus work fine though... so it doesn't seem like the buttons are faulty or anything.
Aside from this the monitor works fine, it's just annoying to have it at 100% brightness.
I haven't been using this monitor in a few months - my brother has, and he reported the same issue - I just came back home and found it like this.
EDIT: SOLVED!
I had the option "Color Temperature" in the "Color" submenu set to sRGB. I've set it to "User mode" and now I can change everything!
http://imgur.com/a/3W5ZH
In the first picture I just selected the first submenu.
The options inside it look white (usable).
When I ENTER that submenu though (2nd pic), all the options turn grey - I can't do anything.
The same happens in "Image Setup" submenu.
All other submenus work fine though... so it doesn't seem like the buttons are faulty or anything.
Aside from this the monitor works fine, it's just annoying to have it at 100% brightness.
I haven't been using this monitor in a few months - my brother has, and he reported the same issue - I just came back home and found it like this.
EDIT: SOLVED!
I had the option "Color Temperature" in the "Color" submenu set to sRGB. I've set it to "User mode" and now I can change everything!