[lubuntu] Ubuntu 16.04 freezes; dual monitor setup on iMac

Ever since upgrading from Ubuntu 15.10 to 16.04, I have experienced a lot freezes. These are freezes I could not recover from with ctrl-alt-F1; I had to hard reboot. The freezes occur almost daily, typically 1-3 times per day. My computer is a 2012 iMac i5 with 8 gb RAM and a Nvidia GeForce GT 640M (GK107M); run with a second monitor (Dell) plugged into my thunderbolt/minidisplay port. I use the Nvidia (361.42) driver on my system.

The crashes seem to occur with different programs ruing, although I have recently noted that they often occur when I'm ruing LibreOffice Write in combination with something else. Two of the attached logs (kelog and syslog from two crashes today) make reference to LibreOffice being out of memory. All of the attached logs make reference to "nouveau", which puzzles me since I'm not using the nouveau driver.

Note that I never experienced a freeze before when ruing Ubuntu 15.10, using exactly the same setup. Also, I don't experience these problems when ruing MacOSX (which I don't do much anymore). Finally, I think it may be some interaction with the dual monitor configuration because I have never experienced these freezes when I unplug the other monitor, and I have no freeze issues with Ubuntu 16.04 ruing a single monitor on either of my Mac minis or my Dell xps 13.

- - , .
.