Connection Refused: Connect on Minecraft Server?

Okay, I'd like to start off by saying I'm kind of new to this whole server thing - but I've been able to play Minecraft on my friend's server for several weeks without a problem, using update 1.6.4 (since that was the only one that worked). Suddenly though, it keeps saying Connection Refused: Connect. How do I fix this?

It can be fixed multiple ways but two easy ones are:
1) Join another server for a couple minutes, then disconnect and reconnect to the server you want to join that has the error.
2) Restart Minecraft

There's some fixes that are pretty relevant to your problem here, I used this guide when I had a similar problem:

http://www.minecraftman.com/internal-exception-java-net-socketexception-connection-reset/