I installed Messenger 5.0 earlier this week, and had it working fine. Today,
I had a notification of
a system shut-down while I was away from the computer.

Now when I invoke Messenger, I get an installer process running which
terminates with an assembly component error, but cancelling the process just
sends you back into an endless loop of restarts. Rebooting makes no
difference. No software has been added or system configuration changes made
since the Messenger 5.0 was added. (Tablet PC edition or Windows XP SP1
fully updated).

Any suggestions?