LCD screen on laptop freezes until warm

Hello,

I have a Toshiba P200D Laptop that has had a problem since new. It is a long story but I have a lot of detail of the the problem as well as a lot of trial for what doesn't work. Any new suggestions would be great.
- If the computer stays on ALL the time and never goes into sleep mode the Laptop LCD is fine.
- If the computer sleeps for a few minutes the screen is fine.
- If the computer sleeps for an extended period or is turned off for a long period, i.e the computer is allowed to cool off, the LCS screen on the laptop will come on but will "freeze" the picture then will slowly turn all black.

Here's the fun part. After about 10 minutes the computer starts to warm up so the screen flickers in and out a few times over 2-3 minutes. Once the computer has been on for about 15 minutes the screen functions normally again.
Another weird thing is that if I connect an external display it functions normally all the time. Even when the computer first starts up. I'll usually have the screens cloned until the computer is warm enough and then I'll use the extended display.

I've brought it back 3 times for service but they never found the problem and now the warranty is outdated...

PLEASE HELP