Q: iMac can't open anything

It sounds like the hard drive has failed or is failing.

Given the possibility or likelihood of a hard disk drive failure, you may have to

consider services of an authorized independent Apple trained service provider

or depending on the model and build series/year, if you or someone you know

has detailed experience in replacement of internal computer components and

can follow direction, and also understand how Macs are different than PCs,

the use of an online repair guide such as those iFixit.com offers for free use.

•iMac Repair guides - iFixit.com:

https://www.ifixit.com/Device/iMac

There were several iMac models, so anything after 2006 build year generally

would likely be an Intel-based iMac running the core processor by that maker.

Earlier models would have the PowerPC (G3/G4/G5) across early build years.

The main difference would be in how accessible the internal components are

and also the operating system (original discs for OS X install-restore; or later

system versions on their original retail install-restore media) the unit could use.

For iMac computers from 2004 to present, you can learn how to identify it here:

• How to identify iMac models - Apple Support

If the computer does not have at least Lion 10.7.5 installed, it probably would

not be able to access Recovery on boot up, since it likely would not be installed.

Older computer models shipped with the system install-restore DVD, that can

be used to attempt to fix a computer, and also it can be used to start up a Mac

(the one it shipped with) and utilities on that DVD can be helpful to reformat &

prepare a replacement hard disk drive for the re-installation of a new system.

A new replacement hard disk drive would need to be correctly formatted prior

to an attempt to install the system software on it; so that would be a multiple

step process. Those who do this often probably have additional items on hand

to facilitate the expediency of the process + save time. Such as a pro or hobbyist.

An authorized Apple service provider who works on vintage or older non-warrantied

products may have to run some diagnostics as part of the repair to see what else

may be contributing to the failure or symptoms that lead to failure. Hardware can

wear out, so the hard disk drive with moving parts is most suspect.

In most locations where an Apple Store with Genius bar exists, you could set an

appointment or ask if your computer is too old for them to provide preliminary

diagnostic or inspection, to have their opinion on the best process; or contact an

authorized repair service who specializes in Apple Macintosh repairs. There

would be a fee for a repair, and you can discuss the matter & choose options.

The product serial number can help those professionals identify your iMac.

In any event...

Good luck & happy computing!

I haven't taken it to the Apple store yet

Don't bother. They can't/won't look at anything over about five years old.

As K Shaffer says, it is important that we know your exact imac variant to give effective troubleshooting help. Even if the online troubleshooting here cannot help you fix it at home, we can ofter tell what is wrong--useful information if you have to take it to an independent repair shop.

When you used Safe mode how long did you allow it to login? It can take many minutes on a damaged system.

Please retry safe mode with this additional step…

Hold shift at boot to enter safe mode (the login window should state 'Safe boot)'.

When you login hold shift again after clicking the login button. That will disable additional user login items. One of those items can cause a slow login if the software is damaged or incompatible etc. Try other user accounts if you have them too.

Do you have a backup? If so is the backup bootable?

If you can try another disk with OS X installed it may help you work out if the internal disk is failing or if the issue lies with some other piece of the hardware.

If you have no backup & cannot afford to lose the data then you need to work out how to copy that data off the disk. 

Recovery mode (or booting from an Installer disk) & Disk Utility can be used to 'restore' the data from one disk to another if you have a spare disk that is large enough to contain a full copy of the Mac. Ask if you want to try that. You may not have a recovery partition if the OS is old, in which case you must use the install disk to boot to make repairs.

Some other options are to try a few basic resets (these may not help)

How to Reset NVRAM on your Mac - Apple Support (use this to confirm you did this one correctly).

Resetting the System Management Controller (SMC) on your Mac - Apple Support

Apple hardware test will be on the original grey install disk that shipped with the Mac.

Using Apple Hardware Test - Apple Support

You may be able to reinstall OS X, that process can restore damaged system files leaving your data intact, however older OS installers do not work the same so please do not do that unless you have a full backup & can tell us what OS version you have installed.

Rachel Schenck wrote:

…

now I'm thinking it may be the start up/login items. How do I start up from the CD and turn off the start up items?

You don't use the OS install disk for this, you use safe mode as I mentioned earlier.

Try safe mode if your Mac doesn't finish starting up - Apple Support

That disables the third party startup items & many nonessential Apple items too. Just be aware that poor graphics performance is not abnormal in safe mode…

Limited graphics performance in OS X recovery or safe mode - Apple Support

Also see this, it is similar to are mode but only deals with items that run in you user account as you login…

https://support.apple.com/kb/PH14201

Personally I still think you need to backup the data ASAP & try using another disk - they do not last forever. Also can you tell us what OS version we are dealing with?

Can you see what version is printed on the OS CD/DVD? Something like 10.x.y or maybe a 'cat name'.  Is this the grey disk that shipped with the iMac or another disk that was purchased after the iMac (normally these have a cat or X printed on them).

I think your best option is to try booting from your backup (connect it, boot holding 'alt' & select the orange backup disk in the boot picker).

If that works OK it indicates issues with the internal disk.

If it fails to boot then your backup is not functional (assuming it should be a fully bootable backup) & you need to consider making a new one.

You can still run Apple hardware test to check out the hardware, but it can fail to catch errors & may not report others. I think the priority is to be sure the disk is not the issue & to validate the backup to be sure the data is safe.

There are also ways to backup from a OS installation CD/DVD, so ask if you want to do that. You will need a volume large enough to hold all the Mac data, ideally with no important files on it (it's safest to erase the disk).

How recent is the backup?

Does the backup have any other user accounts for you to login to for testing? It could be your user account at fault.

When you login on the backup can you eject the internal disk so that it is not in use? If the OS behaves when it is ejected it could be that the internal disk is causing the issue.

It looks like both installations are behaving the same so reinstalling is one option, I would consider installing to a separate hard disk just to test that the Mac can work. It is possible that a hardware failure is causing both OS installations to fail in similar ways. Since the backup was a copy of the internal OS it may be damaged in the same way - some errors will be transferred to the backup.

I'm a little wary to erase & reinstall on older Macs since the hardware may be failing.

'10.4.8' doesn't really answer my question – is this the grey disk that shipped with that Mac? If so read the fine print on the disks to use Apple hardware test. It may detect errors that can help you focus the testing.

In Apple hardware test there are 2 modes – normal & extended. You should run both of them to see if anything crops up.

There is also a loop mode that is enabled by hitting cmd+L. Enable that & try each mode & let it run for a few hours to see if anything happens when it warms up. Photograph or log any errors for searching later.

To eject disks open a Finder window & select the disk in the sidebar. Right click it (or ctrl+click) & select 'Eject "Disk name" '

You can also open the 'Computer' view from the Go menu if you cannot see the disk in the Sidebar & eject it from there.

If you can boot up, login & create a new user it may be worth testing. 'System Preferences > Users & groups' is where you add new users. If that completes reboot & login as the new user. If the Mac is stable we can consider looking at your user account, but it seems unlikely since safe mode & the disabled login items didn't help earlier

When you logged in & held shift that disabled the user login items. Try that again if you like.