Something's wrong with LDAP, and your config.
Try
zmcontrol stop
ps auxx | grep zimbra (kill any left over processes)
su root
chown -R zimbra:zimbra /opt/zimbra/*
cd /opt/zimbra/libexec
./zmfixperms
su zimbra
zmcontrol start
tail -100 /opt/zimbra/log/mailbox.log
post that |