7354 Views 3 Replies Latest reply: Aug 11, 2008 2:06 PM by AndyO
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This is not a problem that is likely to be associated with an overheating failure - typically that would give you symptoms of high revving fan and unexpected shutdown. Restarting the system would then fail while it was still hot, but it would boot and run apparently normally from cold, only to shut down again when it got hot.
I presume when you tried to boot into safe mode, you got the same symptom of grey screen with logo, and no spinning icon or further progress?
In this situation, the first thing I would do is try and perform a PRAM reset:
-Shut down the computer.
-Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in the next step but one.
-Turn on the computer.
-Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
-Hold the keys down until the computer restarts and you hear the startup sound for the second time.
-Release the keys.
If the system does not then start normally, insert the original install disc for the system, and attempt to boot to that by holding the C key down during startup. If the system fails with the same grey screen, then I suspect you have a hardware fault. A possible culprit is RAM, though hard drive failure is also a possibility.
If the system boots to the installer, you have a reasonably functional system, so that's a good sign, but you may have some hard drive issues. Thus you should select Disk Utility from the Utilities menu in the installer, and with the internal drive selected, click on 'Repair Disk'. That would attempt to identify and resolve problems with the hard drive.
If that doesn't help, please describe what the system does, and particularly what you see on screen in as much detail as possible.
Thankyou - I tried pram but to no avail so I went on and used the original disk and tried utilities> repair disk but it now says, "repairing disk failed with error could not unmount disk"
I tried unmounting the disk before repairing it again and it then displayed the a message saying that it couldnt not unmount disk sucsessfully, I then tried repair disk once again and it seemed to be working, it now says
Verify and Repair disk "macintosh HD"
Checking HFS Plus volume.
Checking Extents Overflow file
CHecking catalog file.
Invalid note structure. (font is in red)
Rebuilding catalog B-tree (font is in green)
The volume Macintosh HD could not be repaired (font red)
ERROR: The underlying task reported failure on exit (again the font is in red)
1HFS volume checked
1 volume could not be repaired because of an error
Repair attemped on 1 volume
1 volume could not be repaired
The errors in Disk Utility indicate corruption on the hard drive which is critical to the functioning of the system. The 'error on exit' message and the report that errors could not be repaired indicates that Disk Utility itself cannot repair the problem.
There are basically two possible issues. The first is a mechanical/electronic fault in the drive which means it is failing or has failed, and the second that some action has corrupted the drive but that aside from data corruption, the drive is perfectly healthy. In the first instance the solution is to replace the drive, since it is malfunctioning, but in the second, there are somewhat less dramatic ways to set about resolving the issue.
The first thing to note is that since the system booted to the installer and was able to run Disk Utility, it is basically healthy.
It is possible that the error on the drive can be repaired by somewhat more sophisticated disk utility software such as Alsoft's DiskWarrior. The problem is that such software is not free - meaning you'd have to spend the approximate $100 to find out if the fault is resolvable or not. There's nothing wrong with spending the money, and both Disk Warrior and Tech Tools Pro are excellent utilities that can be very useful to have around, but there's a less expensive and more immediate way to see if the drive is basically OK, and that's to use the install disk and Disk Utility to perform a complete Erase and Install of MacOS.
Because Erase and Install (accessible as an install option by clicking the 'Customize' button in the installer) reformats the drive and installs a brand new copy of MacOS, it means that any corruption issues on the drive are wiped off. If the drive is healthy but has merely suffered corruption, this is therefore the fastest way to get the system back into useful service. The problem is, of course, that in reformatting the drive, it wipes all data, files, music, photos and applications etc., that you may have on the drive, so is generally not something you'd want to do unless you have a good backup.
If you do have a backup, or can either dispense with data you had saved, or don't have anything important on the drive anyway, I'd go ahead and perform the Erase and Install. If it completes successfully then you have a working system and merely need to monitor it for a while to make sure the drive isn't going bad. If the erase and install fails, then the drive is almost certainly faulty and needing replacement.