I have a Dell E6410 used primarily with Ubuntu 12.04, dual boot into Windows 7.
Within the last few days (and without knowingly changing anything) the laptop display has stopped displaying correctly. The image is still visible, but pale, with fine white horizontal lines, and text is distorted as if alternate rows of pixels were missing.
Using F2 at boot shows the Natural Resolution as 1440 by 900, as does the Ubuntu nvidia-settings. However, I'm fairly sure that the display hardware is the 1280x800 version. Certainly the behaviour is consistent with forcing 1440 horizontal lines onto a display that only has 1280.
The appearance has the same problem when booted into Windows. An external monitor works perfectly.
Is it possible that the machine has got confused about its own resolution? If so, how can I correct it? If not, are there other diagnostics I should try?