"System program problem detected" error

[Newhere]

Another lightdm error here:

ERROR: apport (pid 5527) Thu Feb 28 13:14:52 2019: executable: /usr/sbin/lightdm (command line "lightdm --session-child 13 20")

ERROR: apport (pid 5527) Thu Feb 28 13:14:52 2019: is_closing_session(): no DBUS_SESSION_BUS_ADDRESS in environment

ERROR: apport (pid 5527) Thu Feb 28 13:14:53 2019: wrote report /var/crash/_usr_sbin_lightdm.0.crash,

Error Message at Startup

Been running Ubuntu-Mate 18.04 LTS for a few months now with no problems. Keeping everything updated, etc. The last 2 weeks at Startup I get this: A box that's 3 5/8" wide and 1 5/8" high. It's mostly White in color w/a black header. Inside the White box it states: SYSTEM PROGRAM PROBLEM DETECTED, Do you want to report the problem now? And there is 2 option Buttons: Cancel w/a Red X and Report Problem.. I have always Reported the Problem..! Never heard or received any comments, etc...