Sophos Anti-Virus for Windows 2000+: installation error 'Cannot be installed due to some registry keys not having permissions'

Issue
During installation you see an error message similar to,

Error 3004 - Sophos Anti-Virus cannot be installed due to some registry keys not having permissions

Sophos product and version
Sophos Anti-Virus for Windows 2000+

Operating system
Windows XP Professional SP2

What to do

You must open the Windows registry and check that certain keys have the correct permissions. Before you start ensure that,

you have read the warnings about editing the registry
you understand how to apply registry permissions. Details are given in knowledgebase article 13811.

Check the following registry keys ensuring 'Administrators' and 'System' have full control:

HKEY_LOCAL_MACHINE\SOFTWARE

HKEY_LOCAL_MACHINE\SOFTWARE\Sophos

HKEY_LOCAL_MACHINE\Software\Classes

HKEY_LOCAL_MACHINE\Software\Classes\Interface

HKEY_LOCAL_MACHINE\Software\Classes\Typelib

Once the permissions have been correctly added to the keys, you should be able to install successfully.

If you need more information or guidance, then please contact technical support.