1) Reboot and log onto the machine as local admin. Copy the profile of the local user.(old user profile) Name it “copyofusername” or something similar. (optional)
2) Join the domain (under local admin as Domain Administrator). Reboot. Login as Domain Admin.
3) Add domain users to local admin group. Log off.
4) Log on as the domain user. Reboot.
5) Log on as domain admin. Rename the new domain profile to “username.domain.old” or something similar. Rename the “copyofusername” file to whatever the new domain user profile was called. Log off.
6) Log on as domain user.Note: Everything should work as it did before. You may need the users email username and password.