Drive mapping

I am trying to map an NT Workstation to another domain automatically. But before I can do this, I need to get rid of a mapping that is already mapping automatically. I have checked the autoexec.nt, script folder in the netlogon directory, the startup folder in windows, and cannot find the source of this mapping. What can I do to wipe the mapping slate clean and afterwards, in what manner should I map a drive to another domain when the workstation is set to automatically login to its workgroup.