Ativa wireless G router. Hey, you were trying to help me out with me problem so here comes the

Question

Hey, you were trying to help me out with me problem so here comes the full explanation (you were the one who seemed to undestand what's going on)
I have a laptop (acer aspire) wich I use to connect to the internet with my Ativa router. I put a security password on my router so nobody can connect to my internet but me.
Whenever my laptop IS plugged in everything works perfect, it will automatically connect to my internet. the problem comes when my laptop ISN'T plugged in. It won't connect automatically and when I try to connect to my internet it says that the security key is not correct.
It's king of cofusing to me since is the same laptop I'm using so i have no idea how to make it work. All I know is that the hole laptop idea is not to be plugged in hahaha and I cannot use it that way

Please please please answer me back as soon as you can!!!
Thanks a lot!!!!!!!! =)
Lu