I have two monitors side by side under Windows 7. I used to have an "extended" desktop using both monitors, but the right monitor no longer works that way.
Both monitors work if I "duplicate" the desktop on both monitors, but only the left monitor works when I try to use an extended desktop. Also, if I try to put the desktop only on the right monitor, the left monitor doesn't work at all (no image).
Since the right monitor does work if I duplicate the desktop, I don't think there's anything wrong with the monitor itself, the cable, the graphics card, etc. I've checked that the drivers and the software are up to date.
Any suggestions?