I can't play online. I can only play solo. I have bought Minecraft so it should work fine, but, when I try to connect to a server, it says:
Internal client error: java.net.UnknownHostException: session.minecraft.net
I have tried over 20 different servers and it says the same thing for every single one.
Note: These are not Hamachi servers. I'm attempting a direct connection.
Best Answer
Quote from Kristoffer Jelbring, the Mojang web guy: "If you get an UnknownHostException when trying to join a MC server your DNS record is most likely outdated."
See this link for instructions on refreshing your DNS.
Source: Twitter @KrisJelbring