Arctanus

So I accidentally placed what I think was a Magma Crucible right next to a Quarry. Don't do this.

Check this out, see if it helps. http://forums.technicpack.net/threads/crash-on-mojang-screen-fix-confirmed.43909/

I believe the owner of Optifine doesn't allow it to be put in modpacks. Probably so you have to go through his download link and make him money, which is perfectly reasonable.

First do this, leave the IP= blank and try and connect with 127.0.0.1. If you still can't get into your server then, then there is something actually wrong with your server and not the IP you're trying to use. Then change the IP= to the IP that Hamachi gives you, and change Online-Mode=True to Online-Mode=False.

Are you using the 1.5.1 version of Optifine?

Remove the Server IP, it'll default to the correct one if you leave it blank. You're going to have to use two different IPs to connect, one that you give to people who are outside your network, and one that you give to people that are inside your LAN. The one you give to outside people is your external IP, you can get it by googling "What's my external IP." and google just tells you. To connect to your own server you're going to use your internal IP which is given to you by your router. Open CMD and type "ipconfig," look for the IPv4. It'll look something like 192.168.1.x. Another trick is to use 127.0.0.1, which will always connect directly to your own computer. If your server is up and running correctly then 127.0.0.1 will always connect to it. Edit- Scratch my first instructions, I didn't read that you were using Hamachi. In that case you will fill in the IP= section with the IP that Hamachi gives you, which you probably already did. Test direct connect with 127.0.0.1 and see if you're able to get in. Edit2 - If you or your buddies are still not able to connect give this a shot. http://www.mpgh.net/forum/386-minecraft-server-advertising/247750-how-make-your-own-minecraft-server-hamachi.html