During boot up it gives all the symptoms of the back light not working, ie screen very dark can just about see that it is booting up.
If you wait and can just about see the "Press Ctrl alt Del....to logon" then logon to the network.
Once the user profile comes up suddenly the light gets turned on and all is well.
I have tried to get an external monitor so that I can get into and see the bios but no avail. Bios only appears on the laptop screen.
Oh its a Toshiba Satellite Pro
My wife's nephew dumped a glass of water onto his Macbook, and apparently killed the LED backlighting. However it still boots up into OSX - holding a good-sized flashlight to one side, I can see the bootup progress very dimly.
What I suggest is that you try the same, with a 3 or 4-cell flashlight. Start the bootup process and hit the Del, F1 or F2 key (whichever your lappy uses to access the BIOS), and then see if the BIOS has the backlighting set to a minimum brightness or "off" level, and of course change it to a higher level. My Dell lappies can set the default brightness in the BIOS, but the absolute minimum level is still bright enough to where you can see it. Of course, once it boots into Windows, either Windows or the Dell Quickset utlity changes it from the BIOS default, so I suspect the same may be happening with yours according to your symptoms.