I am coming from riak and redis where I never had an issue with this services starting, or to interact.
This is a pervasive problem with mongo and am rather clueless
The cause by me was the space - run this in the console:
df -h
or more specifically:
du -hs /var/lib/mongodb/
to check he disk usage. If it's ~ 99% - just clean up some space and try again!