Flashing Folder Question Mark Question

Question

Hi all,
So on Wednesday this past week, I came into the office, started up the computer, went to get a cup of coffee, came back and found the flashing folder icon with a question mark in it. I used my iTouch to access the web, look for solutions and, as expected, tried to start up from the install disk. I couldn't find the original disk that came with the iMac, but happened to have a 10.5 install DVD so I popped that in, restarted, and waited.
After a minute or so of not doing anything, it promptly gave me that dark grey screen of death, the one with the error message saying "You need to restart your computer" in four or five languages. (Ah crap, I said.) So I shut down and when I restarted, I held down the Eject key to get the 10.5 DVD out. The computer started up normally. No problems.
I promptly backed up everything, repaired permissions, but had no other problems with the computer the rest of the day or all day yesterday.
This morning, I come into the office, same problem. Only this time I hunt down the original install disk that came with the iMac. I start it up and I'm able to get to the install screen. First, I select "Choose startup disk." My hard drive is not visible. I run disk utility. Same deal. No hard drive. Ah crap I say. So, I shut down the computer, restart it while holding down the Eject key. The install disk spits out, and the computer restarts normally.
(I'm backing everything up and running disk utility now.)
Anyone have any idea what's going on here? And, is it time to panic?
Important details: it's a 24 inch iMac purchased a little less than a year ago. It's running 10.5.7 and the last time I updated the software was probably Tuesday, or whenever the new iTunes was released.

Answer 1

As you have not actually seen the onset of the problem, there's still a question of the exact sequence of events (i.e., did the office cat prance on the keyboard?). However, the fact that you get the question mark disk icon (which means the firmware is not finding a bootable drive) twice now, but eventually manage to get the system going leads me to believe the drive may be failing. Odd, but not unheard of; my old PBG4's HDD failed three weeks after purchase and was replaced under warranty.
First order of the day, as soon as you get the thing working again is *BACK EVERYTHING UP* Try to get a suitable sized external drive and do a bootable clone of the startup volume; you can use SuperDuper!, CarbonCopyCloner or even Disk Utility for that purpose. Note that, in a pinch, you don't need a disk the size of the internal drive, you only need the size of the used portion: do a *Get Info* on the Macintosh HD desktop icon and look for the Used: item.
With your system, applications and documents safe, open Disk Utility, click on the device (item above Macintosh HD) and check the +S.M.A.R.T. Status+. If it says anything different from Verified, the HDD has some form of physical damage and should be replaced. Since the Mac is under warranty, you should get in contact with an Apple Store or Apple Authorized Service Provider ASAP before the one-year base warranty runs out (did you purchase AppleCare?).
If the HDD checks out as Verified, get your original Install DVD #1, stick it in, reboot and hold down the D key before the chime. That will load up the Apple Hardware Test diagnostics, which you should then run to verify all the computer. Report back what you find.