I don't know if this is a driver or windows issue.
I have a dual-boot, Dual monitor set up. My monitors are a HDMI BenQ monitor and a DVI HP Monitor connected to a AMD Radeon 6950 card.
Under Linux Mint 64-bit everything works as it's supposed to. The HDMI monitor is the primary monitor with the DVI monitor extending the display.
Reboot to Windows 7 64-bit. Both monitors work during the boot sequence then the login screen comes up on the second monitor and the first shuts off saying no signal. Logging in and the second monitor is acting as the primary and the primary is still off.
This is a recent problem as i have been using the computer in this configuration for about 4 years with no problems. Yesterday, the Windows side of things decided that the primary monitor did not exist.
Under control panel's display AND system device manager only the HP monitor is listed. I have tried uninstalling and reinstalling the Catalyst drivers several times, including clean installing them. When the drivers are uninstalled and Windows falls back on the generic drivers after the reboot, the primary monitor is on and the display is duplicated on both. Install the drivers, reboot, and I am back at square one.Reboot to linux mint and it works perfectly.
There have been no hardware or software configuration changes recently, and the fact it works in Mint leads me to believe its not a hardware issue.