You could try resetting the SMC and PRAM.
None of this will damage your computer in any way. The PRAM stores the current volume, brightness, and the startup disk preferences. The SMC controls the fan speed, along with other things, and resetting it may solve your problem.
First, shut down your MacBook. Now press the power key, and right when it turns on, hold Command+Option+P+R simultaneously. Your computer will restart and you'll hear the startup chime. Keep holding the keys down until it restarts again. You can let them up when you hear the startup chime. Let it boot up and shut it down. Now try booting into Windows. If that doesn't work, it may be the SMC.
To reset the SMC, shut down your computer if it isn't already. Make sure your Magsafe charger is plugged in to your computer and a power source. Now hold down the left side Shift+Control+Option and press the power button. You should notice the light on the Magsafe flash briefly. Now you can let up the keys.
Try booting into Windows. If it still doesn't work, it is very likely a problem with your Windows installation, and you'll have to reinstall Windows.
