I have an Imac core duo too, and because I guessed my OSX 4.11 was corrupted, because was slow; some -5 minutes- at the start up and had problems reading DVDs, all these symptoms started when I tried to back and forward some scenes from a rip DVD movie using the VLC player. 3 times this movie freezes the mac, but at the third try of rebooting to continue the watch, the Imac started to reboot to a blue screen.
My choice was to create a new user, and this helped to reboot again, but with the problem of the slow start up.
lately I bought a new Hard drive to replace this one, that I thought was corrupted.
But the new Hard drive, a Seagate Barracuda 500gb (3g/s) was not recognizable by the OSX disks at the moment of install the OSX into the hard drive. The HDD icon in the set-up displayed a caution sign over the hard disk icon, which normally have a green approval slash to determine the disk is OK for installation. The operation was'nt possible.
Then, after some time using the Old HDD with the slow start up issue...the HDD show new bad start up, so I decide to erase and put the OSX back into the same old HDD using the original Installation disks.
The fist try was good, all 2 disk were installed, but when the imac asked for online updates as the update was happening the computer started to slow the normal interface movements, as moving icons and folders.
And when I tried to start up again the Imac started up in blue screen only.
Then trying to install the disk was not possible, the disks or the HDD fails to write or read the installation, I was clueless. And After a few tries the Installation disk where ejected out of the drive.
The only way to reinstall and read the OSX disk was to enter disk in Hardware test, then restart from its interface and turn on key "C" to install the OSX. Disk1
Installing the disk1 was possible, asking when installed for the disk 2, as normal. But the Disk 2 installation had problems from soome point. Always stucked in the Iwork'06 software installation step in the progress bar.
I have tested this original HDD as an external drive in another mac, and all seems to be Ok with the hard drive.
But when I try to connect the Imac (with the original HDD inside) to an Ibook through a Firewire cable in "T" option, That HDD appears only in the Disk utility interface, but not in the desktop in the Ibook. I can't make installation this way because Ibook G4 PPC and Imac Core duo are not compatible processors.
I bought a new HDD WD like the original internal HDD, but the same problem as with the Seagate.
All these 3 HDD are Sata II or III randomly, ironically I saw reviews in which my original WD HDD it's a SATA III, but it's just because of the transfer (3GB/s) perhaps the Imac is from early 2006 production date.
I have no idea what is causing the problems here, any hint, idea or solution?