strange new warning at shutdown

Hi all,
After a great experience with Calculate on a test laptop i decided to make it my goto os on my main laptop. I have mate configured to my tastes and everything seems very stable. But more often than not, after saving my work and shutting down my programs when i try to shutdown the machine i get an error message i hadn’t seen before. It says at-spi-registryd-desktop failed to shutdown and i may lose work if i continue. If i choose wait it goes on forever. If i choose shutdown anyway it eventually does so with no apparent data loss. Truthfully it sounds like some systemd thing, but i am not using systemd, right? Any advice on what this is, and suggestions for a fix much appreciated. Thx.