doesnt open because of the missing file l guess

Hi, l cant turn on my MAC. It holds on the start screen with Apple. I did fsck in single volume but couldn't repair and said has been modified. Also warned INCORRECT BLOCK COUNT FOR COM.APPLE.POWERMANAGEMENT.PLIST and invalid sibling link. Then in verbose mode said
Launchctl: something like "correct with" if l remember well
Launchd: /etc/mach_init.s/dashboardadvisoryd.plist
At the end telling
Airport: link down on en1. Reason 1(unspecified)
Please tell me detailed what to do..l need. Thanks.

1. Buy Disk Warrior. You'll need the bootable disk to do this. I think it costs $100.
2. Run it.

That should fix that problem, at least temporarily. You may have a failing hard drive that is the true cause of this issue. If DW fixes the problem, MAKE A BACKUP IMMEDIATELY.

Also, it's Mac not MAC. It's not an acronym, it's a nickname (short for Macintosh).

First of all, thanks.
I actually am surprised u have immediately seen my typing mistake..surely l know it is mac for Macintosh...but since l type from the mobile, it wrote in big letters l don't know why..as u remember l don't have a computer now..
Second, is there any other solutioncheaper :S

A cheaper solution - maybe. But since you can't repair the errors on the hard drive with FSCK that means it won't be repairable by using Disk Utility from your recovery DVD. Disk Warrior is expensive but it can repair problems that FSCK and DU can not.

Your hard drive is likely failing anyway so you probably should be prepared to buy a new one and reinstall. But it's best if you can save the data on the failing drive which DW may be able to do.

Thank you, l passed to windows so it is easier to write now than the mobile.
l saw some other programmes like DW but free versions, but l couldn't get an idea if they are ok and enough the free versions. for example Disc Drill...or l saw smth like data rescue and some others.. also the things lm afraid to loose in computer now, are some photos and music files, l have the most important ones in my camera, l dont think need to spend now, so may be l ll risk my computer with formatting. l dont think l ll need to buy a hard drive, because windows bootcamp is working..just snow leopard is failing. formatting solves it right?

Formatting is a drastic step since it wipes out all data. However, if you don't mind losing what's on the drive, go ahead and do a format and reinstall. Sometimes the Boot Camp partition can be OK, but the drive is still failing - however, slowly. Just be sure to make backups so that you can recover if you have to buy a new drive.