we experienced this issue in 2010, but i never got around to fully documenting the cause and solution.

after a planned ESX host reboot, the host would not reconnect to vcenter (no matter how much time went by).

/var/log/messages shows:
Sep 22 10:26:05 esx14 xinetd[3078]: START: vmware-authd pid=25229
from=127.0.0.1
Sep 22 10:26:05 esx14 xinetd[3078]: EXIT: vmware-authd status=255
pid=25229 duration=0(sec)
Sep 22 10:26:08 esx14 xinetd[3078]: START: vmware-authd pid=25281
from=127.0.0.1
Sep 22 10:26:08 esx14 xinetd[3078]: EXIT: vmware-authd status=255
pid=25281 duration=0(sec)
Sep 22 10:26:12 esx14 xinetd[3078]: START: vmware-authd pid=25331
from=127.0.0.1
Sep 22 10:26:12 esx14 xinetd[3078]: EXIT: vmware-authd status=255
pid=25331 duration=0(sec)

vmware support determined that the problem was related to iscsi vmkernel ports that were recently removed in vcenter. despite being removed in vcenter, the ports were still listed as bound to this host’s iscsi adapter.

commands to list and remove:
esxcli swiscsi nic list -d vmhba#
esxcli swiscsi nic remove -n port_name -d vmhba#