Laptop runs off battery even though A/C is plugged in!! Disharges, then switches off?

Hi My Laptop has strangely stopped working off AC power. Normally its the battery that goes on these things! In this case however the battery seems fine and charges normally, however when using it, even when plugged in, the battery slowly discharges and then the laptop switches off even though its plugged... show more Hi

My Laptop has strangely stopped working off AC power. Normally its the battery that goes on these things!

In this case however the battery seems fine and charges normally, however when using it, even when plugged in, the battery slowly discharges and then the laptop switches off even though its plugged in?

Does anyone know what could be the matter or if there is anything I can do to fix it?

The laptop is a 2005 gateway model and does not work at all without the battery plugged in.

Do I need a new battery or A/C pack, or could it be something more sinister??

Cheers
Ben
9 answers 9