Ubuntu :: Sendmail Causes Home Directory To Disappear

I wrote a script that is run by cron every 5 minutes, but for some weird reason it causes my home directory to disappear for any currently logged-in sessions. If I SSH in after that, my home directory will be present but once the cron job runs it will disappear again. This is the script:

Code:
if [[ `ps aux | grep '[m]otion.pid'` = "" && ! -e /tmp/ignore-motion ]]; then
echo "security cameras offline" | mail -s "" xxxxxxxxxx@xxxxx.com
fi

And there are a lot of these errors in /var/log/syslog:
Code:
Jul 14 07:51:01 burbank sendmail[16241]: p6EEp1I5016241: from=ian, size=397, class=0, nrcpts=1, msgid=<201107141451.p6EEp1I5016241@burbank>, relay=ian@localhost
Jul 14 07:51:01 burbank sendmail[16251]: My unqualified host name (burbank) unknown; sleeping for retry
Jul 14 07:51:01 burbank sendmail[16241]: p6EEp1I5016241: to=ian, ctladdr=ian (1000/1000), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30397, relay=[127.0.0.1] [127.0.0.1], dsn=4.0.0, stat=Deferred: Connection refused by [127.0.0.1]
Jul 14 07:52:01 burbank sendmail[16251]: unable to qualify my own domain name (burbank) -- using short name
Jul 14 07:52:01 burbank sendmail[16251]: p6EEq1Pq016251: from=ian, size=397, class=0, nrcpts=1, msgid=<201107141452.p6EEq1Pq016251@burbank>, relay=ian@localhost
Jul 14 07:52:01 burbank sendmail[16251]: p6EEq1Pq016251: to=ian, ctladdr=ian (1000/1000), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30397, relay=[127.0.0.1] [127.0.0.1], dsn=4.0.0, stat=Deferred: Connection refused by [127.0.0.1]

I understand that sendmail is having trouble because of my hostname, but why would it cause my home directory to disappear?