I have a brand new laptop I installed Windows 7 RC on and it will not boot up unless the power cord is plugged into the system. I have tried it on numerous times. The laptop runs fine unplugged after it has booted up with power.

B -Assuming you've got a good battery in the laptop. Now, before you installed Win 7 RC on it, did it work properly with whatever OS the laptop came with?If the laptop is unplugged when you hit the power switch, do you see the manufacturer's splash screen before Windows starts loading? Do the lights flicker? Or is it dead as the proverbial door nail until you plug it in?

Yes it has an excellent battery and yes it worked with the previous OS.When not booting up I get the Windows Logo in the middle of the screen and it just sits there until I plug it in to the power cord thne it will boot. I have let it sit at the windows screen for 30 min and it will not boot until it has external power.