Can't shutdown without pulling the plug.

[Bill Stoye]

This is a second request in hopes to be clearer.

I can't shutdown without pulling the plug. After shutting down fine
since the install over two weeks ago, Shutdown hangs at,
"ACPI_power_off_called". 

I've done daily system upgrades since the install, including today;
Installed and configured the 'nvidia' driver and also 'Zinf'. 

What additional information can I pass on that would be of help?

Bill