Installing Sophos Anti-Virus fails on a Windows Server 2008 read-only domain controller (RODC) and you see error 3051 in the Sophos log.
First seen in
Sophos Anti-Virus for Windows 2000+
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.