Okay here's all i know, i updated java a few days ago, and since then, mincraft can't do shit! i made a single player world with a fresh .minecraft just fine, other games like TF2 and Grapple work perfectly! but i can't join a server i really enjoy, and now that i tried installing a few mods (Death chest, extra biomes, improved third person, more stairs, and modloader) it gets stuck at a screen ive never seen before when i tried to make a new world! its the background and a thing that says "Loading world Converting world" thing. and whenever i try to join any server, it just freezes minecraft entirely, i have to use task manager to shut it down :( ANY help would be.. well.. helpful :/

EDIT: i have re-installed java and i'm still getting the same shit with a fresh .minecraft ._. help!!