Hello everyone,i own a Toshiba Satellite P200D-107 PSPBLE with the fallowing configuration:

Processor: Turion x2 ,TL-52 64 bit 1.6 Ghz
Display: 17.3 inch
Graphics: Ati radeon x1200
Ram: 2x512 mb ram(1 gb total) which i upgraded to 1x2000 mb and 1x512 mb (for a total of 2.5 gb)
OS: FACTORY CD WINDOWS VISTA HOME PREMIUM 32 BIT
Power: Running on direct power cable without the battery

Although the pc is quite old its basically new it barely has 1 year of normal usage on it.

PROBLEM:

The screen goes black (no flashing cursor) although the screen still has the backlight running,the laptop is still powered but its basicly in a sort of deep hibernation with fan still running.
The laptop screen will go off 5-10 minutes after windows loads, even if in idle,it also shuts down during os installation.
I`ve tried letting music run and the music stops when the screen goes black so does all hdd activity which i think indicates that its not related to the video chip.

TRIED SO FAR:

1.Opened up the laptop and cleaned any dust processor,now processor temp is max 50, same for the hdd
2.Update the bios from the original to 1.70 - didn`t help
3.Conected external monitor it also shuts down same time as laptop screen indicating its not a screen issue
4.Reinstalled OS multiple times
5.Tested the memory with memtest64 - no errors
6.Tested the hdd with hddregenerator - no errors

What i noticed:

If i leave just one 512 mb ram in the laptop then the laptop will not shut down at all even in windows intensive apps,tried running a game to rule out video card and it works no problem for hours but as soon as i add the 2gb stick or the other origianal 512 stick it will get the black screen withing 5-10 min (or earlier) of entering windows.

It will never shut down in dos mode(like in memtest,hddregen)even with 2.5 gb ram.

After the lcd goes black if i shut it down and then try to power it back up it will not work at all,the screen will stay black with fan running and cd-rom booting,i must absolutely disconect the power cord and re-attach it before it will start up again.

Anyone have any ideas,i`m experienced with pc`s but have never came across something as weird as this,i just can not explain this problem thats came right out of the blue.