I just got a new ipod touch and iwant to connect to the internet. But it never works. HELP PLEASE.?

Whenever i connect to a wi-fi network, it's usually linksys. It always takes like 5-15 minutes and then it says "invalid arguement" what does that mean, and why does it take so long to connect? i have the 3rd gen 8gb model. I really want to go on the internet.