Weird boot issues on iMac Core Duo

[rspeaker]

Back in August, I did an OS update on my iMac, and the machine wouldn't reboot. I was able to reinstall Leopard by booting from a disk, and all was well for a few more weeks. The machine seemed to run normal, with the exception of 5-minute-plus boot up times. But within a few weeks it stopped booting. I installed Leopard on an external HDD and figured I'd leave the internal alone until Snow Leopard came out.

A few weeks later when SL was released, I booted from the install disk, found the internal HDD, and went through the installation process. Everything went fine but the machine would not boot. I installed SL on my external HDD running Leopard, and everything was fine. I've since been running my computer off the external.

The internal HDD no longer shows up on the desktop, in Disk Utility, etc. I'm fearing it may have died. More worrisome, though, is my machine doesn't always boot up, whether from my external HDD (set as the startup disk) or from CD. By "doesn't always boot up," I mean most of the time when I restart, it just sits on a gray screen, nothing happens (even when holding "Option" or C.) Sometimes it will boot, but takes 20 or 30 minutes to do so.

I'm considering replacing the internal HDD, but am curious, does that seem like the issue, or might the failure to boot from externals and CDs indicate a more serious problem?

 

[Eidorian]

Hard drive failure if it's easy and a logic board issue if it's hard.

 

[ziggyonice]

If you’re seeing a gray screen and nothing else at startup, it’s a problem with the booter. The booter (or boot file) is what allows the computer to even access your files to begin with. If the boot file is bad, that could be what’s causing the grey screen issue. The easiest way to fix it is to just reinstall the OS. I’d recommend backing up your files to another external drive, and then wiping the external and reinstalling the OS.

As for your internal HD, I think it might be done.

 

[rspeaker]

This has happened a few times before, too. In iPhoto, when editing, the screen goes green like this, and I have to back out of editing, and the picture reverts to the original (even if it was previously edited and saved successfully.)

I'm thinking video card. I'm also thinking my machine is dying, and swapping the HDD won't be the fix. Thoughts?

(I may end up swapping the HDD just to see, but I don't have much technical know-how, and money is an issue. So if it seems like the computer is dying, it might not be worth the time and money and I'll just use it till it goes.)

 

[jared_kipe]

Your internal hard drive is dead/dying. Problems on the SATA and EIDE busses will prevent option+boot and other things from working correctly. The computer is waiting to receive information from devices that have turned on, such as your dying hdd, and since they are dying they either do not give the requested information or do so with errors, thus slowing down EFI's ability to boot at all correctly. Seen it a dozen times on macbooks with bad hdds, and with alumiMacs when their Opical drive is dead.

As far as iPhoto's inability to correctly render its output, this is more likely an iPhoto problem, or rather a corruption of data. Could try rebuilding the thumbnails and what not by holding option while launching iPhoto. (I think)

If it were graphics card problems you'd be seeing evidence in other places, such as kernel panic log backtraces to the graphics card driver. Or corruption while doing other things. For instance why is there no corruption with the alpha overlaid adjustment bar?
Because there isn't a graphics card issue.