Reset Windows Update Agent variables via sysprep

Open you sysprep.inf file with notepad and add lines below under [GuiRunOnce], if you don't have [GuiRunOnce] you can create it. If you have already command under this section you should re-number commands below like Command6.../

This will run the commands below once at system startup after image applied and delete previous entries from the image you have taken, and the agent will re-generate new SusClientId for you.

Command0="reg.exe delete HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate /v PingID /f"
Command1="reg.exe delete HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate /v AccountDomainSid /f"
Command2="reg.exe delete HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate /v SusClientId /f"
Command3="reg.exe delete HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate /v SusClientIDValidation /f"