While working at my last job I've come across this a lot. Windows simply stops connecting to the internet when you try to open IE (Internet Explorer) or Fire Fox. This really isn't an issue anymore since most people have broadband internet.
Under the Control Panel:
- Double Click 'Administrative Tools'
- Double Click 'Services'
- Double Click 'Remote Access Auto Connection Manager'
- In the Startup type: pull down menu, select 'Automatic'
- Click the Start button.
The next step is to make sure that you have a connection already configured and that it's set to autodial:
- Start->Settings->Network and Dial-up Connections
- Ensure that there is a dialer or create one if there isn't
- Select the Dialer
- Click the 'Advanced' pull down menu
- Select 'Dial-up Preferences...'
- Under the Autodial Tab, enable the 'Enable autodial by location' checkbox
Optionall, if you sometimes connect to a network and use dialup:
- Start->Settings->Network and Dial-Up Connections
- Click the 'Advanced' pull down menu
- Select 'Advanced Settings...'
- Under the Adapters and Bindings tab, in the Connections: window, choose the order for DNS to use (LAN or dialup adapter)