At&t wireless router 2wire 2700hg-b

This may seem strange this router has two computers on the nework one is a laptop. Both computers can access the internet. the problem is that only the laptop can access email accounts like gmail or yahoo. I believe the other computer needs something set to do his, but I dont know what or were to check. it can go to the gmail log in page or any other internet page but cant load the gmail messages page when you enter your log in details. This is also the same for any other mail message pages as i set up a new account in hotmail on the laptop but couldent get to the messages from the other computer. The browser on the desktop is firefox but internet explorer is also installed annd can be used. Firefox is set as the default browser. Has any one any ideas how to fix this so i can access email fom the desktop.