What do the "System Sleep Mode Enabled" and "System Sleep Mode Disabled" messages displayed in the lower-left corner of the PC Access screen mean?
These messages are related to a new feature that was added in PC Access 3 version 126.96.36.1992. The feature, "Prevent System Sleep While On-Line", which can be found under Options>>General, can be used to keep a PC from going to sleep while an active connection is established between an Omni or Lumina controller and PC Access.
They are just a notification that when you disconnect, PC Access has re-enabled the system sleep mode so the PC can go to sleep normally. There should be a similar message when connecting, notifying that sleep mode has been disabled, although it might be overwritten quickly with other connection messages.