This printer has been working just fine [UM 16.04] until today .
cups-pk-helper-mechanism crashed with signal 5
I needed to print so I booted into Ubuntu 14.04 to prove either software or hardware - 100% software [same printer, same computer, same connection]
Note this is an Ubuntu 16.04 [with MATE desktop added] install prior to official release. Maybe it’s time for a fresh install.
Hi Pete,
do you have this package installed which might help?:
sudo apt-get install hplip-gui
I have an HP printer and they can be flaky now and then!. 
Thanks for the suggestion Stephen - I have hplip-gui installed on both machines - only the tower has the problem - MATE desktop added to an Ubuntu 16.04 install… PLUS the install was prior to 16 official release.
It’s a minor inconvenience to boot into Ubuntu 14.04 or go to my laptop just to print but
a guy’s gota do what a guy hasta
I’m going to install fresh in the same test partition after a while so maybe I can document exactly is wrong [possibly an update along the way will fix it]. My gut tells me that applying MATE desktop over top of a vanilla Ubuntu install probably is the culprit - another indicator is when using nautilus on the machine my screen gets funky - I logout and log back in to straighten it out.
The tower with MATE added to Ubuntu might be test case interesting @Wimpy and if so I’ll dedicate it and some time to dive deeper.
###I have a perfectly behaving UM 16.04 install on my laptop that was fresh after release.