I tried to solve this problem by adding prepend domain-name-servers xxx.xxx.xxx.xx as suggested in many forums.
However, this solution didn’t work for me.
I solved the problem by editing /etc/dhcp3/dhclient.conf and commenting all lines involving the directive “request” (no prepend necessary):
#request subnet-mask, broadcast-address, time-offset, routers, # domain-name, domain-name-servers, domain-search, host-name, # netbios-name-servers, netbios-scope, interface-mtu, # rfc3442-classless-static-routes, ntp-servers;
I love Ubuntu, but it’s irritating that they keep breaking previously working stuff…