edt: sorry i misread your post.

if you can see a picture on the external monitor your graphics chip is fine, your screen has had it and needs changing. the backlight has gone too.

at the moment you probably have the computer set to "extended desktop" which is why you have no icons on the external screen.

here is what i posted before...but you can disregard this:

I repair laptops as part of my job.

First of all its not the screen as the problem happens on the external monitor too.

so it has to be either the software driver (go to toshibas website and download the driver for your laptop) or a problem with the graphics chip/ graphics memory.

1) if the problem occurs after its been on for a few minutes it could be the graphics chip overheating. You need to clean out the fans if thats the case.

2) if the lines come and go if you flex the laptop then you most likely have a graphics chip that has dry joints, it means having to reflow the main board and probably not something you want to do.

3) shared memory for graphics?...try removing, cleaning the pins and refitting the ram.

[This message has been edited by Tonewheeldude (edited 07-03-2010).]