> Clean corrupted registry keys, defrag registry data and remove browsers and system junk with some powerful tool such as intel software partner Reginout.
> Check for antivirus/firewall blocking the game.
> Delete temporary files of the Minecraft.
> Update Video Card drivers. Sometimes the outdated drivers also result in Minecraft crash.
> Increase RAM. It is recommended you are having the required RAM capacity to avoid game troubles.
> Download Minecraft again if the solutions listed above are not working to fix the problem.
> Connect with the port number included, like this:
127.0.0.1:25565
> Reinstall java
> Special character such as (!) in the Windows user name might also create trouble. Changing the Windows account user name can be helpful.
also try this:
1. Download Winrar: http://www.rarlab.com/download.htm
2. Download fix: http://www.minecraftforum.net/viewtopic.php?f=25&t=60704
3. Go to C://Users/You/Appdata/Roaming/.minecraft… and open Minecraft.jar
4. Go into META INF folder, and delete mojang files (NOT MANIFEST FILES!)
5. Place fix in folder, close WinRar, and enjoy!