Installing Sophos Anti-Virus fails on a Windows Server 2008 read-only domain controller (RODC) and you see error 3051 in the Sophos log.
Sophos product and version
Sophos Anti-Virus for Windows 2000+, version 7.5 and above.
Windows Server 2008 (32-bit) Standard RODC
What to do
Installation fails on a read-only domain controller because the installation program cannot create an auto-update account.
You must create the AutoUpdate account manually so that Sophos Anti-Virus can automatically download updates.
Once created, ensure that the user credential is cached on the read-only domain controller.