XP: TV8 not working - had to revert to TV7

[fxm]

Running TV7 on XP, I attempted to initiate a session and was prompted to upgrade to TV8, which I did.
I was then not able to connect - even to the 12345 demo.
I uninstalled TV8, rebooted, downloaded the setup program and (re)installed.
Still no joy.
I uninstalled again and installed TV7, which works fine.

The primary problem with TV8 was that Connecting.../Authenticating... would start but never finish.

The secondary problem was that when I exited TV8 after the above happened, a process called Teamviewer_service.exe was left running [Task Manager shows it using 50% CPU].  That process could not be killed and - so long as it was running apparently - another instance of TV8 would not launch.