Macbook Won't Startup - No Entry Sign; Have to reset thru Safe Mode.

Press the Power Button and immediately press and hold down the Command and the S keys as the machine starts up. This boots you into Single-user mode and you should see white text appear on the screen.
When you see the # Command prompt, type /sbin/fsck-fy and hit the Return.
Now sit back & let your computer do its thing. This should take approximately 15 minutes or so. Depending on how messed up your computer is. Just be patient.

If and when you see the message File System was modified repeat the steps above again & again until you hopefully see the message no problems were found." When that happens type reboot and hit Return again.

If these steps do not work then boot from your install disc to repair disk. To use the Install Mac OS X disc, insert the disc, and restart your computer while holding down the C key as it starts up.
Select your language.
Once on the desktop, select Utility in the menu bar.
Select Disk Utility.

Select the disk or volume in the list of disks and volumes, and then click First Aid.
Click Repair Disk.



From Apple's Knowledge Base
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Message was edited by: CMCSK

Is there a way to for a reinstall of the EFI/SMC firmware?

Not that I am aware of.

Or is there a way to reinstall the *Mach Kernel?*

Had to do a Google search for that one. The definition was waaaaaaaaaaaaay over my head. Another user will have to answer that one.

When you say you replaced the hard drive, did you restore from a backup?
If resetting PRAM/NVRAM and repairing the disk doesn't fix it, then you need to reinstall the OS.
The no entry sign means critical boot files are corrupted or missing. Restoring from a corrupted backup will not fix the problems. You have to install over the top of the current installation or erase and start over.

Any more input on this issue? I've had the same problem (starts in safe mode, cannot boot diagnostics, etc.), but strangely it disappeared and then reappeared recently. I thought this might be indication of a hardware problem, but I have no way to test it. TechTool pro says the memory and disks are clean.

Anyway, would really love to hear other people inputs before I go through the trouble of archiving/installing.

Thanks!