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For those that nothing works try to remove everything under /Library/Preferences/SystemConfiguration and reboot. Keep in mind you will loose any custom network configuration such as VPNs or static IP/DNS entries.

Nope, that didn't work either. Guess I'm gonna have to re-install everything. Tried all suggestions.

vitalyishim THANK`S I SOLVED IT

LefterisT, that did the trick. Thanks!

thanx this worked perfectly!

Thank you very much,you are the best

Thanks you, LefterisT.

8.8.8.8 has solved various problems for me before. It did the trick on this Facetime problem.

Tim, I can't tell you how many hours I spent of my Saturday trying to fix this Facetime/Messages issue, and how many things I tried from so many helpful people. But only yours worked. Playing around in Terminal scares me since I know nothing about it, but I was able to follow exactly what you wanted me to do and--aside from a detour to figure out why my hosts file wouldn't unlock, even as an administrator--it worked perfectly. I could kiss you. I would if you were here. (But don't be scared... I'm a good kisser.) Thank you, thank you, THANK YOU!

I hate to say it but I may have spoken too soon! Facetime and Messages have now both given me some trouble, both having shut down a few times with an error message. Worse, another issue has arisen in the old one's place. When my Mac goes to sleep now, it wakes itself up at some point, and is completely unresponsive. The screen is dark. I've had to do a hard shut-down four times, each time it's happened. Tonight after work, I turned it on again and put it to sleep. It stayed asleep for an hour or so, but at some point, when I was away from it, it turned on again and the same thing: black screen and unresponsive.

The only thing I can think of at all is the fix for Facetime and Messages. Any idea why this would happen? As you suggested, I made a copy of the original 'hosts' information. Can I reverse the process by putting it all back? I'm trying not to freak out but Terminal already made me nervous since I didn't know what I was doing and I wonder if I've created a mess...

Whoops...*looks sheepish* I forgot to follow your last command, which was to swap the hosts file on the desktop back in. I'm hoping that now that I've followed directions properly that my issue will right itself. 🙂