Rackspace Backup stuck in Queueing state

If your backup is stuck in a queueing state and being skipped the next day because of an already running instance, the problem may be due to a crash or unexpected reboot.

Make sure you do not have a state lockfile located at:

/var/cache/driveclient/backup-running.lock

after shutting down the daemon, this shouldn't exist.

Thanks to Evan B @ Rackspace for the quick pointer!