While trying to get Windows Vista to work I have messed up my partitions. When I go to bootcamp to restore to single volume it says it can't. It tells me to go to Disc Utility and and format my disc. To reformat my disc do I go to erase? If so it will not let me, everything is greyed out. If I choose Macintosh HD it will let me erase freespace but that is all. What should I do?!