I disabled Millenaire and now it all works just fine again. Too bad since it looked like such an awesome mod. But thanks anyway you have been a great help!
That fixed it but now the game itself is very unstable. When I am ingame (I created a new world) the game crashes like every 5 minutes.
new ForgeModLoader-client-0 part 1: http://pastebin.com/EHuFKZhY
new ForgeModLoader-client-0 part 2: http://pastebin.com/wfaNzdtT
I am using the X Mod Pack 2.0.1 (http://xmodpack.weebly.com/) which works just fine but as soon as I install Millénaire 3.3.2 (http://millenaire.org/) the game crashes on startup.
The Forge version in use is the one that comes with the X Mod Pack (minecraftforge-universal-1.4.6-6.5.0.472.zip)
ForgeModLoader-client-0: http://pastebin.com/rNZ272FJ