Wag54g2 connecting to computer

Hi
I have a WAG52G2 which connects to the internet ok - all the appropriate lights are up. When I click on a browser, Firefox or IE, the browser screen comes up and tries to connect to Google, my default homepage. Nothing further happens. 30 minutes later I MAY be able to connect without doing anything further. Even tho' my browser won't connect, Skype can and will do so immediately after boot up. I have upgraded the firmware to v17 ok but nothing has changed. I can connect a second computer to the router, the computers can talk to each other but neither can connect to the internet except after a period of time. Rebooting & powering down the router makes no difference. One computer runs under Vista the other XP SP2. Any suggestions?