When I came back from vacation, I could not start up my Cloudera Sandbox. It failed with the error message:
problem with the configuration server (/usr/libexec/gconf-sanity-check-2 exited with status 256
To fix it, press CTRL+ALT+F2 to switch to a Linux Terminal and then login with root, then change the permission of /tmp to 777.
Restart it. All good to go.