Sophos Anti-Virus for Windows 2000+: installation error 'No versions of component 'MessageResDSFactory' are registered'

Issue
When you attempt to install Sophos Anti-Virus for Windows 2000+, version 7.6, the following error is displayed:

No versions of component 'MessageResDSFactory' are registered. MessageResDSFactory cannot be returned.

There may be an additional message, error, or warning relating to a permissions/group membership issue. This is a false warning.

Sophos Product and version
Sophos Anti-Virus for Windows 2000+, version 7.6

What to do

Open a command prompt and type,

regsvr32.exe "C:\program files\sophos\Sophos anti-Virus\localisation.dll"

In order to do this, you may need to remove yourself from the "sophos admin" or "sophos user" groups and then add yourself back.