I've got 2 machines that I am getting this error on.

They where previously registered, but I reimaged them to an image containing no Zenworks Agent. Before I reimaged I deleted the machines from the database via the web interface.

I reinstalled the agent, and then tried to register them and recieved this error.

I have tried the following :
zac cc
zac fsg -d
ZISWIN Clear Image Safe Data
Delete the GUID from the HKLM\Software\Novell\Zenworks\PreAgent

I suspect that something has gone wrong in the removal of the machines from the database, and that this is why they are failing. Is there any way to manually check the database to remove these machines ?