Minecraft Stopped Running due to exception generating new Chunk

Earlier on today i was making a new map with mcedit, after the completion of the map i saved it and checked if it worked in Minecraft itself, which it did after a few hour i tried again and no matter what world i load or create it gives me this error.
Only mods are Optifine and world downloader both up to date
And where it says my Os is Windows 7 (amd64) it isnt.
And everytime when i try to assign more memory on vanilla and modded, there is no affect and remains at 1gb