Genius Bar Can't Replicate Problem - What Now?

Whether they can replicate it or not, I would have them run a full diagnostics on your machine to make sure there's no more hardware issues.

Which iMac? When was it bought? Does it have AppleCare extended plan? Do note that for desktops with AppleCare, if you're within 50 miles (80 KM) of an Apple repair station, you're eligible for onsite repair since yours is a desktop machine. BTW, before taking it home, have them fire it up and see if you can get it to act up.

I'd try running memtest to test the RAM. The "Geniuses" may not have had the patience or interest in testing the RAM long enough. Finding RAM errors can be very tricky. The next time it freezes, see if there are any messages in Console in Utilities from around the time of the freezes. Look in system.log and scroll through elsewhere to find anything under "Diagnostic." Copy them if they exist and and show them those.

To test the memory, get memtest and run it in single user mode, where it will test as much memory as possible, more than with the OS loaded.

You can get memtest + directions from the link below. However, ignore running it from Terminal. Instead, boot into SU Mode, Cmd-s at the startup chime. (Best to startup from a full shutdown.)

At the prompt, simply type /usr/bin/memtest all 3 -L Observe case and spaces.(From this link It will be installed in /usr/bin/) Then hit return. This will run three loops of memtest and create a log in Console in Utilties.

If you want to run memtest longer, which may be advisable, since RAM errors can be very elusive, just remove the "all 3" which will give you /usr/bin/memtest -L and hit return. It will keep testing until you quit it.

If you want to quit the test, just hit control-c

When finished, you can just type in "reboot" and hit return.

http://osxdaily.com/2011/05/03/memtest-mac-ram-test/

Direct link for the download.

http://cdn.command-tab.com/2008/memtest_422.zip

I suggest Rember. It has a later version of that executable and a GUI front end/

Can you check your AC outlets at home?

Anything connected at home that wasn't at the store? Did they use your Mouse & KB?

baltwo wrote:

I suggest Rember. It has a later version of that executable and a GUI front end/

mentest in single user will test more RAM. But what's the later version number?

They're both 4.2.2. So, Rember provides a GUI for the same version.

memtest in single user is dead easy to use. The OP just has to follow the simple directions above. Will test much more of the RAM, since the OS isn't loaded.

It is possible that something in your environment is causing or contributing to the problem.

How often does the problem happen? Is there anything you can do to get the problem to happen? When the problem happens do you notice anything happening in the environment (lights dim or flicker, room is warmer then usual, etc)?

Try placing the computer in a different location for a time to see if the problem occurs. A different room would be best. Do you have the computer plugged directly into the wall socket? Getting a surge protector might be something to try.

As a last resort if you have a way of videoing taping (iPhone or other device) then recording the system while the problem is happening and showing that to the technicians might be helpful.

good luck