Java8 fixed a bug (well, lots of stuff I assume, but one bug fix in general is the problem) that broke forge (I know, ironic right?). Well, you have a few options. You can downgrade your java version and play fine, or attempt to patch forge to work with the current java version. Here is a thread with the details. http://www.minecraftforum.net/forum...-forge-1-6-4-1-7-2-java-8-compatibility-patch