Perhaps this is some help.
I had rollback issues. Only on 1 PC with W7/SP1.
Somehow I found that I still had a Windows Home Server folder in "Program Files" (in addition to the Windows Server folder that V2 installs) with all of the files for the V1 connector, discovery.exe, etc. that had not been deleted when I unistalled
V1 months ago.
When I tried to delete the folder, it wouldn't go away due to one of the files being open somewhere else.
I looked at the processes including the "Show processes from all users" and realized the old WHS v1 was still loading and running a connector process.
I had to boot in safe mode to get rid of it, it would not respond to "end Process" from the task manager.
After that the new connector installed just fine.