I have a strange problem. I had something fall on my laptop closing the screen down forcefully. Now when I boot the computer the screen is scrambled. It is not scrambled during the BIOS screen or the boot screen, but scrambles once it is booted. Moreover, if I connect an external monitor with a VGA cable the screen on the laptop goes back to normal and the external monitor works. If I unplug the external monitor the laptop screen scrambles again. Plugging in just the VGA cable without the external monitor leaves the laptop screen scrambled.
My guess is that the monitor ribbon is loose (though it will be some time before I can open up the laptop to check that), but if that were the case I don't understand why connecting an external monitor with a VGA cable would fix the laptop monitor. Any advice would be greatly appreciated.
The Laptop is a Dell Inspiron 1501 running Windows 7
