In the network services area of the control panel, you;ll see a list of your connections. In the "LAN or High Speed Connection" area, you'll see "Bluetooth networking" Right click on it and choose properties. The proerties window will show you the name of the connection and services used in a small window. this list of services shouls be:
Client for microsoft networks
File and Print sharing
Tcp/IP
Double click on TCP/IP and you'll get a box like so:
In the Ip box enter a new number.
the number should be 192.168.0.X, where x is a number between 3-5. 1 and 2 are used by your router and network card and are thus taken. When bluetooth tried to use an in use the same ip address, it took down your network.
In a pinch you can also simply righ click on "Bluetooth networking" in the network panel at the top here and choose "disable" since your phone can't use network access via bluetooth (that's for palms and PocketPC's)