I just downloaded the latest Galacticraft version 3.0.10.301 from the downloads page, ran it on my PC in Minecraft 1.7.2, and like all the other versions it ran 100% OK in 1.7.2..
I am not sure what you two guys are both doing wrong?
Please carefully check, are you running Forge version 1147, in the vanilla launcher from Mojang, as shown in the screenshot here:
http://wiki.micdoodle8.com/wiki/Tutorials/Galacticraft_Installation_Guide#Step_4
If it still doesn't work for you, test using a smaller set of mods, maybe one is conflicting? I would start by looking at MCPatcher.