I bet that vpnc has overwritten /etc/resolv.conf and it has lost the backup file to restore it.

Check that /etc/resolv.conf has contains following single line:
nameserver 127.0.0.1

edit:
and reason for losing the file is that /var/run is actually /tmp/.run which is volatile memory ie. it gets lost when shutting down. Shut down vpnc connection before turning off the tablet or before battery runs out