failed to query tcp_ip

So first up, restart Windows into Safe Mode with Networking. To get there you need to hit F8 when it's booting up but you need to do it before the Windows logo appears. If the logo has appeared then you're too late and will need to reboot again.

Once you're in safe mode, edit your registry (Start button, run, regedit). Locate and delete the following keys completely:

HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Winsock HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Winsock2
Open c:\windows\nettcpip.inf and find the [MS_TCPIP.PrimaryInstall] section. It will look something like this:

[MS_TCPIP.PrimaryInstall]
    ; TCPIP has properties to display
    Characteristics = 0xA0 ; NCF_HAS_UI | NCF_NOT_USER_REMOVABLE
    AddReg          = Registry.MS_TCPIP.PrimaryInstall, Registry.MS_TCPIP, Registry.MS_TCPIP.Legacy
    RegisterDlls    = MS_TCPIP.Register
Change the Characteristics = 0xA0 to Characteristics = 0x80 and now it will look like this:

[MS_TCPIP.PrimaryInstall]
    ; TCPIP has properties to display
    Characteristics = 0x80 ; NCF_HAS_UI | NCF_NOT_USER_REMOVABLE
    AddReg          = Registry.MS_TCPIP.PrimaryInstall, Registry.MS_TCPIP, Registry.MS_TCPIP.Legacy
    RegisterDlls    = MS_TCPIP.Register
Open the network properties of the connection you need to fix. In the General tab, click the Install button, select "Protocol" then click the "Add" button. Click the "Have Disk" button, enter "c:\windows\inf" in the text box and hit enter (the OK button remains greyed out but hitting enter works). Now select "Internet Protocol (TCP/IP)" and click OK. Note that you do not want "Microsoft TCP/IP version 6" - the one you need should be at the bottom of the list.

Now that you've done all this, you can uninstall TCP/IP in the network properties dialog. So go back to the network properties, scroll down to "Internet Protocol (TCP/IP)" and click the uninstall button. If you have Simple TCP/IP services installed you'll need to uninstall them first (the dialog will tell you this). To do this you need to shut the network properties dialog down, then go to the Control Panel, select "Add or Remove Programs", "Add Remove or Windows Components", select "Network Services", click "Details", uncheck "Simple TCP/IP Service", then ok etc.

My machine skyrocketed to 100% CPU usage after I tried to uninstall TCP/IP and nothing seemed to happen. I let it continue not doing much for about half an hour and then tried Ctrl+Alt+Delete to bring up the Task Manager but everything was pretty unresponsive. So I hit the power off button and then booted up again.

Despite me pulling the plug, TCP/IP was removed when Windows started up again so I was able to reinstall it using the steps above (from "Open the network properties of the connection you need to fix"). On reboot networking was all working nicely again, so I was able to install two network adapters, reinstall McAfee and I was ready to go again.