Thank you for your help. I set up a masternode.conf file (I don't recall that being part of Tao's guide when I set these up in September 2015) and now this masternode stays online when the wallet is closed. I still do not know what my problem was but this fixed it...
I have a masternode up and running for a while now (16 months) but it is not paying out recently despite being listed at dashninja.pl ip 45.32.1.44. Last payout 5/24/2016. Dash version 12.8.56. This happened to this one masternode (no others) after I upgraded my masternodes ot 12.8.56. Others...