To disable WPAD in Windows, you'll need to make an easy registry edit, as StackExchange user laktak points out:
Click the Start button, and in the search field, type in "regedit", then select "regedit.exe" from the list of results.
Navigate through the tree to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Wpad.
Once you have the "Wpad" folder selected, right click in the right pane, and click on "New -> DWORD (32-Bit Value)".
Name this new value "WpadOverride".
Double click the new "WpadOverride" value to edit it.
In the "Value data" field, replace the "0" with a "1", then click "OK".
Reboot the computer.