Wierd Flashing Display Problem with Inspiron E1405

Ok, I've never seen anything like this. In a nutshell: The Dell display only works when plugged into an external monitor. That's right, the LCD on the laptop comes on only when an external monitor is connected. However, there are 2 exceptions: 

1) If I pull a memory chip out and restart it, It will tell me the system memory has changed- that screen works fine without an external monitor plugged in

2) The post screen also shows up fine, but then all hell breaks loose on the Microsoft splash page when the screen starts flashing and flickering.

Based on this behavior, I figured it was a Vista problem, but even the BIOS screen is a nightmare, with both screens rapidly flashing in alternation, I feel like I'm going to have a seizure. The Windows login screen does not display on either monitor. The only way I can get it to show up is to shut down the computer by holding down the power button, wait 10 minutes while it does a Startup Repair, and then it will show the login screen. From there, I can get into Windows but as soon as I pull out the VGA cord, I lose the display on the laptop.

Anyone ever heard of anything like this?