Dual Monitor Issue

Hi, I have a rather specific and yet glaring issue that's recently come up after some modification to my MacBook Pro mid-2010 running Windows 7. I run W7 on a second hard drive that I installed in order to add more storage space to the 128 GB SSD that I use for its speed.
The problem is, I use an external monitor (connected via DVI from the MiniDisplayPort) that works all of the time except when I try to use it as the only monitor. I'm able to run both at once, or just the laptop's screen, but when I close the laptop and try to use only the external monitor, the monitor claims it's not receiving a signal. The CPU fans are still running, and the keyboard lights are on, so I assume the computer is running, there's just no picture going out. Alternatively, when I used the Nvidia settings to switch the external to main monitor, the same thing happened until I unplugged it and it used the laptop screen again.

EXTRA INFO:
This issue only came up recently, after I switched from a 500GB 5400rpm extra HD to a 750GM 7200rpm HD. I tried doing a clean install on the partition that I made for W7 to fix this issue but it didn't work, and neither did a driver uninstall/reinstall.
I also believe a part of the cause may be the attempt I made to install Kubuntu, during the partitioning stage I accidentally did not make the partition for Linux large enough for Kubuntu so the install failed. The next time I turned on the computer, I was forced to run a chdisk on startup and reboot, at which point it worked again.

I'm willing to try a complete wipe of the HD (which I did not do before in order to save the data I had on another partition) if that could help, it would simply take a long time.

Thanks

I think it might have something to do with when you shout the lid on the laptop. Once the lid is closed there is no power to that screen and subsequently no power to 2nd monitor because of the lid being closed. There might be a setting to change/play with on the laptop as to what happens when you close the lid of laptop.