HELP!!Macbook freezes during startup

[crazy4mac]

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!

 

[deadpixels]

yes, if DU doesn't see your startup disk, it's kinda bad. if you have a DiskWarrior startup disk you could try to startup with it and see if it can fix your HD. or you could try to start in safe mode, see here