The auto-update accounts used by Sophos Anti-Virus Small Business Edition (SBE) to install and update Sophos Anti-Virus on Windows 2000, Windows XP and Windows 2003 computers are automatically generated with an encrypted key during installation. The passwords on these accounts cannot be changed.
If these accounts are deleted or altered then updating will no longer work.
What to do
Uninstall and reinstall the affected computers.