I used Chris's deb package and it is much better now. Ubuntu 8.04 on VMware Fusion. It drops out after an hour which is certainly than a minute. :)

From /var/log/syslog
Jul 13 22:22:44 work vpnc[23446]: connection terminated by peer
Jul 13 22:22:45 work dhclient: DHCPREQUEST of <null address> on eth0 to 192.168.23.254 port 67
Jul 13 22:22:45 work dhclient: DHCPACK of 192.168.23.129 from 192.168.23.254
Jul 13 22:22:45 work NetworkManager: <info>  DHCP daemon state is now 3 (renew) for interface eth0 
Jul 13 22:22:45 work dhclient: bound to 192.168.23.129 -- renewal in 862 seconds.
Jul 13 22:23:52 work kernel: [51580.301176] tun0: Disabled Privacy Extensions
Jul 13 22:24:13 work vpnc[24927]: packet too short from 216.31.250.90
Jul 13 22:24:53 work last message repeated 2 times
Jul 13 22:25:53 work last message repeated 3 times
Jul 13 22:26:53 work last message repeated 3 times
Jul 13 22:27:53 work last message repeated 3 times
Jul 13 22:28:53 work last message repeated 3 times
Jul 13 22:29:53 work last message repeated 3 times
Jul 13 22:30:53 work last message repeated 3 times
Jul 13 22:31:53 work last message repeated 3 times
Jul 13 22:32:53 work last message repeated 3 times
Jul 13 22:33:53 work last message repeated 3 times
Jul 13 22:34:53 work last message repeated 3 times
Jul 13 22:35:53 work last message repeated 3 times
Jul 13 22:36:53 work last message repeated 3 times
Jul 13 22:37:07 work dhclient: DHCPREQUEST of <null address> on eth0 to 192.168.23.254 port 67
Jul 13 22:37:07 work dhclient: DHCPACK of 192.168.23.129 from 192.168.23.254
Jul 13 22:37:07 work NetworkManager: <info>  DHCP daemon state is now 3 (renew) for interface eth0 
Jul 13 22:37:07 work dhclient: bound to 192.168.23.129 -- renewal in 779 seconds.
Jul 13 22:37:13 work vpnc[24927]: packet too short from 216.31.250.90
Jul 13 22:37:53 work last message repeated 2 times
Jul 13 22:38:53 work last message repeated 3 times
Jul 13 22:39:53 work last message repeated 3 times
Jul 13 22:40:53 work last message repeated 3 times
Jul 13 22:41:53 work last message repeated 3 times
Jul 13 22:42:53 work last message repeated 3 times
Jul 13 22:43:53 work last message repeated 3 times
Jul 13 22:44:53 work last message repeated 3 times
Jul 13 22:45:53 work last message repeated 3 times
Jul 13 22:46:53 work last message repeated 3 times
Jul 13 22:47:53 work last message repeated 3 times
Jul 13 22:48:53 work last message repeated 3 times
Jul 13 22:49:53 work last message repeated 3 times
Jul 13 22:50:05 work dhclient: DHCPREQUEST of <null address> on eth0 to 192.168.23.254 port 67
Jul 13 22:50:06 work dhclient: DHCPACK of 192.168.23.129 from 192.168.23.254
Jul 13 22:50:06 work NetworkManager: <info>  DHCP daemon state is now 3 (renew) for interface eth0 
Jul 13 22:50:06 work dhclient: bound to 192.168.23.129 -- renewal in 880 seconds.
Jul 13 22:50:13 work vpnc[24927]: packet too short from 216.31.250.90
Jul 13 22:50:53 work last message repeated 2 times
Jul 13 22:51:53 work last message repeated 3 times
Jul 13 22:52:53 work last message repeated 3 times
Jul 13 22:53:53 work last message repeated 3 times
Jul 13 22:54:53 work last message repeated 3 times
Jul 13 22:55:53 work last message repeated 3 times
Jul 13 22:56:53 work last message repeated 3 times
Jul 13 22:57:53 work last message repeated 3 times
Jul 13 22:58:53 work last message repeated 3 times
Jul 13 22:59:53 work last message repeated 3 times
Jul 13 23:00:53 work last message repeated 3 times
Jul 13 23:01:53 work last message repeated 3 times
Jul 13 23:02:53 work last message repeated 3 times
Jul 13 23:03:53 work last message repeated 3 times
Jul 13 23:04:33 work last message repeated 2 times
Jul 13 23:04:46 work dhclient: DHCPREQUEST of <null address> on eth0 to 192.168.23.254 port 67
Jul 13 23:04:46 work dhclient: DHCPACK of 192.168.23.129 from 192.168.23.254
Jul 13 23:04:46 work NetworkManager: <info>  DHCP daemon state is now 3 (renew) for interface eth0 
Jul 13 23:04:46 work dhclient: bound to 192.168.23.129 -- renewal in 766 seconds.
Jul 13 23:04:53 work vpnc[24927]: packet too short from 216.31.250.90
Jul 13 23:05:13 work vpnc[24927]: packet too short from 216.31.250.90
Jul 13 23:06:13 work last message repeated 3 times
Jul 13 23:07:13 work last message repeated 3 times
Jul 13 23:08:13 work last message repeated 3 times
Jul 13 23:09:13 work last message repeated 3 times
Jul 13 23:10:13 work last message repeated 3 times
Jul 13 23:11:13 work last message repeated 3 times
Jul 13 23:12:13 work last message repeated 3 times
Jul 13 23:13:13 work last message repeated 3 times
Jul 13 23:14:13 work last message repeated 3 times
Jul 13 23:15:13 work last message repeated 3 times
Jul 13 23:16:13 work last message repeated 3 times
Jul 13 23:16:53 work last message repeated 2 times
Jul 13 23:17:01 work /USR/SBIN/CRON[26055]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)
Jul 13 23:17:13 work vpnc[24927]: packet too short from 216.31.250.90
Jul 13 23:17:32 work dhclient: DHCPREQUEST of <null address> on eth0 to 192.168.23.254 port 67
Jul 13 23:17:32 work dhclient: DHCPACK of 192.168.23.129 from 192.168.23.254
Jul 13 23:17:32 work NetworkManager: <info>  DHCP daemon state is now 3 (renew) for interface eth0 
Jul 13 23:17:32 work dhclient: bound to 192.168.23.129 -- renewal in 836 seconds.
Jul 13 23:17:33 work vpnc[24927]: packet too short from 216.31.250.90
Jul 13 23:18:13 work last message repeated 2 times
Jul 13 23:19:13 work last message repeated 3 times
Jul 13 23:20:13 work last message repeated 3 times
Jul 13 23:21:13 work last message repeated 3 times
Jul 13 23:22:13 work last message repeated 3 times
Jul 13 23:23:13 work last message repeated 3 times
Jul 13 23:23:53 work last message repeated 2 times
Jul 13 23:23:54 work vpnc[24927]: connection terminated by peer