Beam process not running - although service say cb is running

Have installed on Amazon AWS image.
Start instance - most of time it works fine, but occasionally find that CB server not running.
Note: No configuration has been performed at this time - i.e. the node should present the set-up/configure cb screen

Logged into box (52.19.185.11) to investigate
ran sudo service couchbase-server status
and it reports * couchbase-server is running

However no beam processes are running i.e.
ps aux | grep beam
ubuntu 3345 0.0 0.0 10460 928 pts/1 S+ 16:19 0:00 grep --color=auto beam

I have run cbcollect_info and uploaded to http://customers.couchbase.com.s3.amazonaws.com/MB-16227/52.19.185.11.zip

Noticed in the debug.log the following:

[ns_server:info,2015-09-02T11:50:41.427Z,ns_1@127.0.0.1:<0.2.0>:ns_bootstrap:stop:47]Initiated server shutdown