Stsadm -o migrateuser Generates Error "Object reference not set to an instance of an object"

I have been involved in some migration tasks for SharePoint, that includes changing of the domain name. SharePoint has quite easy ways of doing migration, as long as you don't meet some strange error messages (hey, I think this applies to any migration!). I will discuss about the data migration in more detailed, hope by next post (however, if you need some information for data migration in SharePoint, please feel free to drop comment).

So, once you meet strange error message, the data migration is not that easy anymore. One error message that keeps me busy doing research is running stsadm -o migrateuser -oldlogin [oldloginname] -newlogin [newloginname] -ignoresidhistory, that return error "Object reference not to set to an instance of object". I just found out recently that it's actually caused by one SSP with status "Unprovisioning". What I need to do is just to delete this SSP, and, voila, the stsadm migrate user command runs succesfully. =

However, it's not a smooth journey to delete this "Unprovisioning" SSP either. The command that save me is stsadm -o deletessp -title [sspname] -force. The first time I executed this, the command hang for very long time. I try to restart the server, and first thing after restart is to execute this command, and it succeeds.