Boot Camp Assistant forces restart

[travistaylor123]

I am trying to use boot camp assistant to create a partition for a second OS on my macbook. The assistant runs fine until it begins to create the new partition. Then it forces me to restart the computer. When i log back in it give me the "os x quit unexpectedly" message. The space i alloted for the new partition is also gone, but no new partition exists. When i use the repair disk utility it gives me back the space. Any Ideas?