Lab computers losing Internet connection

Occasionally, one or more of the lab computers lose their "external Internet" IP address (range 10.x.y.z) and cannot connect to the net.

[geekspeak]
I think the DHCP lease expires and doesn't get renewed properly. Then some Windows domain controller on the internal network takes over and assigns the machine IP addresses in the range 192.168.x.y, but those IP addresses are useless for accessing the outside network.
[/geekspeak]

The solution is to

1. Login to the machine as "vgadmin" (get the password from Martin)
2. Fire up the command line "cmd", and at the command line,
3. Release the DHCP lease: ipconfig /release
4. Renew the DHCP lease: ipconfig /renew (you may have to do this multiple times until you get no error).
5. Logout