I am using Ubuntu 12.04. After installing VPN client and using it for couple of months normally, something happened. After one more package/program update I stopped being able to connect to Internet without the VPN client - ie I have to be connected through my university VPN even with my home Wifi connection. On Windows XP machine (dual-boot on the same laptop) and android phone everything works just fine.
I got some useful info from this question. I tried adding
to /etc/resolv.conf and that worked. The referenced question (and the file itself) warn that it is auto-generated and will be over-written. My resolv.conf survived a reboot, so I'm not sure when it gets overwritten.
It might be a temporary hack, but it will get you back online for now.