Currently Being ModeratedMar 19, 2012 4:52 PM (in response to akadingbat)
Normally if there is no bootable volume you'll get a flashing '?'. It doesn't sound like you are getting that far. I suggest following the steps in this article to rule out some other common causes of gray screen.
If you still have your Install discs that came with your iMac you can boot from them, then run the Disk Utility application by pulling down the Utilities menu once you select the language. The Disk Utility application will tell you whether your hard drive is visible to the system, and then you can verify whether it is functional.
Currently Being ModeratedMar 20, 2012 3:20 AM (in response to iCare)
I have tried all of this and managed to get it to the stage where I am trying to do a reinstall but when it looks for a destination to reinstall onto the imac can't find anything. This has happened with both the attempt to reinstall from time machine and from the original install discs.
Currently Being ModeratedMar 20, 2012 4:54 AM (in response to akadingbat)
You say you've done everything suggested in these posts.....have you run Disk Utility from your install disc? Does the drive show up in DU? Can you repair it using DU? Your drive may well have failed but it sounds like you have a backup, so all is not lost. Try Disk Utility and consider taking it in for service.
Currently Being ModeratedMar 20, 2012 5:57 AM (in response to Mike Sombrio)
When I do manage to get disc utility to open it reports "First Aid failed" with an "invalid record count" and "Error. The underlying task reported failure on exit" when I verify disc permissions it says "Volume needs repair"!! Any thoughts? Thanks for input folks much appreciated.
Currently Being ModeratedMar 20, 2012 6:25 AM (in response to akadingbat)
My thoughts are that 1. Your drive MAY have failed or 2. More likely the drives directory has become corrupt. Since you have a backup and your files are safe (right?) i would attempt to repair the drive using DiskWarrior. Although expensive it can repair many problems that DU cannot. If you didn't have the backup I would first attempt to recover your files with Data Rescue before attempting any repair with DW. I don't think DU is going to get it done in this case.
Currently Being ModeratedMar 20, 2012 6:28 AM (in response to akadingbat)
You cantake a look at and D/L DiskWarrior here
And Data Rescue here
Currently Being ModeratedMar 20, 2012 7:43 AM (in response to Mike Sombrio)
Thanks Mike I will look at that. I have full back up on Time Machine so Data recovery not a problem.
Currently Being ModeratedMar 20, 2012 9:11 AM (in response to akadingbat)
I read all the stuff for Disc Warrior and was just about to order it and thought I will just try one more thing again so I went for the erase option, this had not worked previously but for some reason it worked this time so I am now reinstalling from the install discs and it seems to be working, then if that goes okay I will bring everything up to date from Time Machine. This is the first time in over twenty years of using Macs I have ever had this problem and it just reminds us all the importance of a) keeping the install discs somewhere safe and b) backing up your data and Time Machine is brilliant for this.
Thanks Mike and iCare for your input much appreciated.
Currently Being ModeratedMar 20, 2012 9:17 AM (in response to akadingbat)
Hope everything goes ok. When you get up and running keep a close eye on SMART status. Also watch for spinning beachballs and other slowing/lagging problems they could indicate returning problems.