The problem of Gray Screen raises normally in Windows Vista System. This is mainly due to changing background theme. You might have installed Windows Blinds and changed the theme. It is the main reason, for the problem. Theme changing and that too by installing Windows Blinds, causes this problems in Windows Vista. This is the problem faced by many in Vista due to Windows Blinds. To get off the problem, you need to uninstall Windows Blinds and remove themes connected to it. You should also be sure that, background images or wallpapers are not in slide show. This might also be the reason for the problem.

I hooked up a Monitor to my laptop and ever things loads fine. The laptop screen is still grey

My computer had a similar issue until now. I resolved it by unplugging the power cord from my laptop and taking out the battery. Then, I pressed and held the power button for approximately 30 seconds. Then I inserted the battery and plugged in the ac power. I turned the computer on and it's back to normal. Hope you find a solution.