Please try going in to the areas below :
If you have just uninstalled and re-installed try rebooting the PC first before checking the below options.
Start > Control Panel > Network Connections > right click on your network connection and click properties> left click on “Internet Protocol (TCP/IP)” to highlight this then click properties, just below and to the right. This is to make sure that the button for “Obtain an IP address Automatically” has a dot in there, as if it's for home you should get your IP from your internet service provider.
If it does do the following
Open internet explorer and go to
Tools > Internet Options > click on the tab that says “Connections” > down the bottom click “LAN settings” If there is a tick in the box that says “automatically detect settings” take this out. Sometimes this can play havoc and sometimes it helps, it’s just one of those things I’ve found.
You could also uninstall Firefox, then restart the computer. Open up IE (if it’s IE7) go to
Tools > Internet Options > click the “Programs” tab > down the near the bottom you will see the check box to make IE your default browser > make it your default browser and restart the PC.
If this works you can then re-install Firefox, make sure it’s the latest version though
http://www.mozilla-europe.org/en/firefox/Let me know how you get on
Rgds,
MM