HHH-ITS will be removing the 'UMN.EDU' login option in the near future, instead you will choose 'AD' from the 'Log on to:' drop-down on the login screen.
This change is transparent and will have no effect on your computer's files or settings. Your computer will remain exactly the same as it was before the switch. You only need to make this switch once per computer. The computer will remember 'AD' for all future logins after you successfully login.