02-16-2009, 09:18 PM

I've had some kernel panic issues with my iMac (specs in sig). It results in a grey screen at startup where it freezes. It often takes up to 20 restarts before it will load Leopard and function correctly. When it finally does boot and run correctly, it only does for a day or two and then the kernel panic returns.

I've done everything I know how to do. This is includes resetting the PRAM, running disk checks, fixing permissions, software updates, etc. I've run the extended hardware test utility and it turns up nothing on the hardware side of things.

I'm assuming it must be software related. I don't mind doing a complete reinstall if it's necessary. I've got everything backed up with Time Machine, so I'm covered there.

Any suggestions?

02-16-2009, 09:21 PM

Have you done First Aid in Disk Utility? Run a filesystem check/repair?

02-16-2009, 09:27 PM

Originally Posted by cwa107

Have you done First Aid in Disk Utility? Run a filesystem check/repair?

Yes. Everything checks out fine. I'll run it again and report back.

EDIT: Here's the results.

Verifying volume “iMac HD”

Performing live verification.
Checking Journaled HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Checking multi-linked files.
Checking Catalog hierarchy.
Checking Extended Attributes file.
Checking volume bitmap.
Checking volume information.
The volume iMac HD appears to be OK.

Verify permissions for “iMac HD”
Reading permissions database.
Reading the permissions database can take several minutes.

Group differs on "private/etc/cups", should be 0, group is 26.
Permissions differ on "private/var/spool/cups/cache/rss", should be drwxr-xr-x , they are drwxrwxr-x .

Permissions verification complete

Repairing permissions for “iMac HD”
Reading permissions database.
Reading the permissions database can take several minutes.

Group differs on "private/etc/cups", should be 0, group is 26.
Permissions differ on "private/var/spool/cups/cache/rss", should be drwxr-xr-x , they are drwxrwxr-x .

Permissions repair complete

02-16-2009, 09:31 PM

Did you run the fsck command in single user mode?

02-16-2009, 09:36 PM

Originally Posted by cwa107

Did you run the fsck command in single user mode?

I don't even know what that is. Care to explain?

02-17-2009, 07:26 AM

It seemed to be working fine last night. I put it to sleep before I went to bed. It woke up to the desktop just fine this morning, but there was no mouse cursor on the screen. I restarted it and now I'm back to the lovely grey screen where it stays frozen... Nice.

02-17-2009, 07:50 AM

Have you tried running Disk Utility >Verify Disk as well? Permissions are fine but the other test will check the HD structure. You need to use the original install disk to start from, if it finds anything that needs repairing. Try Verify and see what comes up.

How about running the Apple Hardware Test off the install DVD? After all these, an Archive and install is making sense as a next step IMO. I would download the latest Combo updater before doing the Archive and Install, as it will get you back up and running faster.

02-17-2009, 08:15 AM

Originally Posted by Cherokee

I don't even know what that is. Care to explain?

Yup, try step 7 in the guide below:

Basic OS X/Mac Troubleshooting

02-17-2009, 08:17 AM

Originally Posted by Chilbear

Have you tried running Disk Utility >Verify Disk as well? Permissions are fine but the other test will check the HD structure. You need to use the original install disk to start from, if it finds anything that needs repairing. Try Verify and see what comes up.

How about running the Apple Hardware Test off the install DVD? After all these, an Archive and install is making sense as a next step IMO. I would download the latest Combo updater before doing the Archive and Install, as it will get you back up and running faster.

I have not run a disk utility off of the install DVD. Unfortunately, I can't run anything off the DVD unless I actually get the computer to boot properly. When it's at the gray screen, it doesn't respond to any commands whatsoever, so the startup DVD is useless.

What's the command for disc utility off the start up DVD?

I have done First Aid in Disk Utility and it showed no problems with the HD.

I managed to run the extended hardware test from the install DVD the last time the iMac booted correctly. It found no problems.

02-18-2009, 10:38 AM

You should be able to boot from the DVD, because it doesn't require the hard drive to run. What happens if you put the DVD in the drive at startup, then restart (control-command-power) and after that hold down the C key or the option key to select the DVD for startup.

It really sounds like a hardware problem if it's intermittent, even if only 1 out of 20 times it's starting. If there are no peripherals attached, I'd try to isolate which piece of hardware is causing the problem. Maybe running the hardware check several times, or a third party program. I'd also ALWAYS check the RAM, reseat it and replace it. This is a quick fix and can eliminate a lot of problems.

02-18-2009, 04:52 PM

Originally Posted by thehumble1

You should be able to boot from the DVD, because it doesn't require the hard drive to run. What happens if you put the DVD in the drive at startup, then restart (control-command-power) and after that hold down the C key or the option key to select the DVD for startup.

It really sounds like a hardware problem if it's intermittent, even if only 1 out of 20 times it's starting. If there are no peripherals attached, I'd try to isolate which piece of hardware is causing the problem. Maybe running the hardware check several times, or a third party program. I'd also ALWAYS check the RAM, reseat it and replace it. This is a quick fix and can eliminate a lot of problems.

I ended up doing an archive and install after every test I ran came up negative for problems. So far, it's doing fine. I'm not extremely optimistic though.

As for booting from the DVD, it would only work if I was able to get the computer to start up properly. Then I could restart, hold down D for the hardware test, C for the install option, etc. It would run properly until I got the next kernel panic. I'd then be back to the gray screen problem

As long as I was getting the gray screen at startup, I could hold down whatever key I wanted and it would do nothing. I also couldn't eject the DVD from the keyboard or by holding down the mouse button at startup. It's like the computer might as well have been shut off. It responded to nothing. I also couldn't see it on my network.

I tried all of these methods of startup with no peripherals plugged in. No keyboard, mouse, etc. It was always the same result.

I had aftermarket RAM in the machine. I put the stock stick back in as I suspected that the RAM may have been the problem. It made no difference and nothing showed up on any hardware tests. I had kernel panics with both sets of RAM.

I guess I'll have to take it in if I have have any more problems. The nearest Apple Store is 2.5 hours away, so it's not something I really want to do. We'll see what happens, I guess...

02-18-2009, 05:05 PM

Originally Posted by Cherokee

I had aftermarket RAM in the machine. I put the stock stick back in as I suspected that the RAM may have been the problem. It made no difference and nothing showed up on any hardware tests. I had kernel panics with both sets of RAM.

Memory problems can be the most difficult to troubleshoot as they can manifest themselves in so many different ways. At one time, I used to buy whatever memory was cheapest, but I've learned my lesson on that and switch to using Crucial. Since that time, I have never once encountered a bad memory module and recommend them highly - even against some of the other big guys like Corsair, Kingston, etc...

What kind of memory was it?

02-18-2009, 05:21 PM

Originally Posted by cwa107

Memory problems can be the most difficult to troubleshoot as they can manifest themselves in so many different ways. At one time, I used to buy whatever memory was cheapest, but I've learned my lesson on that and switch to using Crucial. Since that time, I have never once encountered a bad memory module and recommend them highly - even against some of the other big guys like Corsair, Kingston, etc...

What kind of memory was it?

OWC/Techworks

It has a lifetime warranty, so if the RAM is the problem, I'm covered.

Like I said though, I've had the kernel panic with the OWC, as well as, the stock Samsung stick.