What would make a laptop screen go black after it is completely booted hooked u

Wow. A 5 year old laptop. It could be anything.

Your motherboard could be going/gone. Have you tried taking out the battery, and just plugging in the laptop directly to the wall?

Your laptop could possibly even have dust bunnies/lint/gunk inside which would cause it to short the motherboard.

I would suggest - well the only thing I can suggest is tossing it out. Even computers eventually die.

You could get it possibly repaired - but that would cost much more than a brad new laptop.

I understand that but it is a 1.2mhz processor with 500gb hd 512ram I would have to upgrade ram but other than that it does everything I need it to do. Have reinstalled windows xp so it is a fresh install but still shuts screen off. Was thinking maybe removing the internal battery on the motherboard to see if doing that would help at all.

Could also be the backlight for the screen.
http://www.laptoprepair101.com/laptop/2007/01/31/replac...

As I stated earlier - try unplugging your laptop battery and just plug your laptop directly into the wall see if it starts up that way.

I just mentioned what I said because it might be a lengthy and possibly futile attempt to revive your old computer.

Another thing you could do is - shoot some compressed air into the vents - but I don't really reccomend this as it might just move the dust and junk around instead of expelling it.

The best bet would be to take apart the laptop completely and clean out the insides.