Mac mail only works on 1 wireless network

[thinedude]

Hi. I'm currently running OS X leopard and i'm having some problems with my mac mail. My mail is configured with my gmail account, and when i'm at home, it works perfectly. It receives and sends emails with no problem. However, I'm visiting my parents over the holidays right now and when i connect to their wireless network and open the mail app, i get this message: "the POP server "pop.gmail.com" rejected the password for user "myemail". Then i enter my password as it asks and but it keeps rejecting it. It's not a big deal to go to gmail.com to check my email but it's much more organized in the mail app and i would love to have it work no matter where i connect to the internet if there is a way.