It has something to do with the firewall. On my Mac I got prompted if I should allow Minecraft to allow incoming firewall connections or something like that. (Don't actually remember word for word ) I clicked no and it did the same thing as you stated up there. The next time the prompt came up I clicked "Allow", and the joining server problem was resolved.

Hope this helps!

Bump

When this happend to me I just waited a day and it fixed its self but you seem to have a different problem

Someone?

Have you tried re installing Minecraft? It worked for me one time.. just a mod that I had forgotten

I'm having this issue too

Allocate more memory. If you don't know how.. Google is your friend.

someone?

I have this problem aswell, i just go onto the internet then go back onto minecraft, it is pretty annoying, right?!