reconnect user to active session from a different PC

hi all

i wanted to know how to allow a user to reconnect to active RDS session when he opens rdp from a different PC.

scenario: user connects to RDS from his workstation (and leaves it active) then goes to the conference room and opens rdp again. i want him to "snatch" the active session to the conference room.

my setup: 2 file servers holding UPD, 2 brokers in HA, 2 session hosts

because of the use of UPD when i try to login in the conference room im getting the error: "The User Profile Service service failed the sign-in. User profile cannot be loaded."

any help would be great :)

thank again,

Sean.