Please help me! I have a very important presentation tomorrow, and my macbook is freezing during startup! I have tried to boot from the DISK, then when I check the disk utility there, I can't find my local disk. Only the optical disk and network show up there. Does this mean there is a serious problem about me hard disk? I havn't backed up my files for a while, and don't have a copy of my ppt file. What can I do??? Can any one help me? Thank you very much!