Automatic update checking can be disabled for all users on a Windows system by setting the following DWORD registry value:
AutoCheck = 0
This value needs to be set in the following registry key on Windows 64-bit installations:
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Neumetrix Limited\HttpWatch\Version
This will disable automatic update checking and disable the check box in Tools->Options that is normally available for each user to enable or disable the update checking.
Most Windows installations are 64-bit but if you are using 32-bit Windows the registry value needs to be set in this location instead:
HKEY_LOCAL_MACHINE\SOFTWARE\Neumetrix Limited\HttpWatch\Version