[Login Failure - Unable to resolve host name]

I'm on macbook .. never had problems with the updates before

[Login Failure - Unable to resolve host name]

Every time I try logging into SL a message pops up and says

"Login failed. 

DNS could not resolve the host name.

Please verify that you cant connect to the www.secondlife.com

web site. If you can, but continue to receive this error please go to the support section and report this problem." 

I have uninstalled & reinstalled SL three times. I've tried two different viewers.

Anyone know what I can do?