hey - im not sure if im posting in the right section but i have a problem and would like some help please

i have an intel macbook running osx tiger (10.4.10)
it uses wireless internet from my sky netgear router no problem at all...
so long as its plugged into the charger and switched on at the mains...

when i disconnect the charger my internet stops connecting unless i open i new safari window and load the apple start page again...

so for every page i go to when im running off battery power i have to open a new window and let the apple start page load

its really annoying... any ideas? is it anything to do with powersave?

cheers for any help in advance!