I fixed a brightness issue on my laptop and now when I plug in my external display, it shuts off my laptop's screen, and makes the external display a solid red, green, yellow, or blue... To fix it, I have to force shut-down and re-boot because it won't revert if I unplug the external display. I know the cable is fine because it works when I do this using Windows.
Specs: Acer Aspire V5
um... If you need any more information, tell me how to get it. I'm still learning the ropes to linux (and the way Windows 8 is going, I may switch to linux entirely... W8 sucks, and 8.1 is going to be worse...)