switching users in GUI resulted in failure

[sflower]

Hi all,

I created two user accounts and was setting up directories and permissions for sharing of selected data between the two when I encountered the following situation. Installed is Gnome desktop and Mate desktop. I was using Mate desktop with GDM. I logged into the gui as user one. Eventually switched user via System>LogOut>Switch User. I now logged in to the gui as user two. In the course of working I switched back and forth between the two user accounts using System>LogOut>Switch User. At one point however, when switching from user two to user one the screen hung en route to the GDM login screen. I tried pressing Ctrl-Alt-F2 to see if I could bring up a terminal. It continued to hang. Then suddenly I was back at the user one session without having to enter any password or even select which user to switch to. After a second or two the system crashed and what seemed to be an infinite series of nouveau messages scrolled on the screen. I was forced to do a hard shutdown and restart the system. All appears to be well after restart but I would like to find out what happened and how to report this bug. Where should I look for the pertinent data to report this problem?

Thank you,

Steve