With the Install Disc in place, hold c key or alt key at bootup.
"Try Disk Utility
1. Insert the Mac OS X Install disc, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu at the top of the screen. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Select your Mac OS X volume.
5. Click Repair. Disk Utility checks and repairs the disk."
Hi rknox I was looking for a recent troubleshooting comment mach_kernal appearing on my folder and I deleted it and then the at mark would not function on my key board ,after that I had to use my virtual key board and then some thing really strange ,my virtual keys were typing flashing like when i was doing some work on my external hard disk.
I have read different threads but I just had an up grade too ,but my suspicions are that this is a result of some deep stuff that mac is doing to get new sales of macs going,but then I could be wrong ,anyway what has happened since you re installed I am now thinking this mach_kernal will have to be dealt with by a complete re format and install from Factory settings.
Some have said not to delete it ,well that is too late now.
For you who have had this mach_kernal appear suddenly then therer is some thing in commen we should work together and go to the bottom of this mystery.