When removing Mobile Devices from Exchange Mailboxes, you get the error message: DeviceId cannot contain hyphens.

Scenario:  When you attempt to remove a mobile device from a users mailbox, you receive the error below.

Error:  An unexpected error has occurred and a Watson dump is being generated: DeviceId cannot contain hyphens.  

Resolution: Remove the mobile device object via ADSI Edit.

1. Open ADSI Edit.
2. Under the Default Naming Context, navigate to the user object of the mailbox that has the mobile device.
3. Expand that user object, and click on the CN=ExchangeActiveSyncDevices.
4. Delete the Mobile Device for this user.