normanreed@btin 0 Newbie Poster

I hope someone can explain this to me because I don't understand it at all it, is an ADVENT 7001, turn the power on and the laptop will shut down almost straignt away. Boot to DOS and it sits there for hours but as soon as I go to run a program the same thing happens, laptop shuts down.
Now if I connect an external monitor to it it works fine!!
I don't understand why it is working OK with the external monitor plugged in but not without. The screen, cables and invertor have all been tested and seem to be OK.
Hope someone can help
Norman :o