Last week I was at a customer who had a notebook that refused to make a connection to the internet. In the device manager were a lot of exclamation points next to the network adapters. This pointed me to a problem with tha AVG Miniport Driver, which was strange because AVG was no more installed on that system.

After a thoroughgoing investigation I turned the firewall on and off again. After those simple clicks the problems were solved, the exclamation points were gone and the notebook had a internet connection again.