When a user clicks on the End User Migration button for archive migration from his/her local workstation
This is after/during the installation of the MSI
"Class not registered"
The "Class not registered" error is due to a lack of Windows updates. Ideally your migration machine should have all current Windows Updates installed. If the migration workstation doesn't have internet access you should at least make sure that you're running the latest Windows service pack, the latest Office service pack, the latest .NET service pack and all MSXML updates.
If there is a problem with MSXML 6.0 being installed The issue can be solved by installing MSXML 4.0 SP2.