Since the upgrade, my computer is crashing all the time

I would check your RAM modules and hard disk are seated properly if you are getting kernel panics.

I read the entire thread and still don't know what model you have. Must have missed it.

http://www.youtube.com/watch?v=1Zjzv-mJxFY

Hi polole, IT WAS HARDWARE.

After long attempts I was able to reproduce the problem crashing the system in few seconds.

I followed this steps:

- I created a new clean user

- I opened a pdf with peview

- I imported 20 photos into the new user's iPhoto library and opened iPhoto on one of these photo

- After that I started jumping between preview and iPhoto some times.

- After that I opened a photo and moved (using bottom photos minuatures) around the photos.

This crashed the system.

I got an appointment into an AppleStore and showed the issue.

They identified as HW issue and replaced motherboard in 24 houors (not cheap but very FAST).

Now is working ...

I'll use it and I'll let you know if the problem is gone.

I have read most of this post. It is unfortunate that you do not have an Apple Centre in your country. I had huge problems with Lion (although no kernel panics). After three visits to my Apple Centre, the replacement of my mouse and keyboard, a thorough hardware test (more than is available to ordinary users), and 8 days of intensive testing which found nothing, the Centre did an "erase and Install" of Mountain Lion and all problems (or 95%) have disappeared. The culprit was suspected to be corruption in my User Account.

If I were you (and I know that you have re-installed the OS more than once, I would do an erase and install and proceed as follows:

Download the M.Lion installer again, save that installation routine on another drive (before running it to install the OS itself because the installer is overwritten during the OS installation), use Disk Utility to erase the whole of your internal drive, install the OS itself on your internal hard drive (by running the installer from the external), create a User Account, and (assuming you have the time!) run the computer intensively for several days on nothing more than what has been installed (eg, Safari by browsing and setting up Favourites etc.,, Mail but with no emails set up yet, TextEdit, Preview, Grab, Notes,iTunes (but without adding any music) QT Player (with some good quality movies), and any other apps or utilities that the OS provides. Don't add email address, Calendar data, or copy docs, pictures, music or anything from the old backup. No printer driver. You want to have a virgin bare system running with just the minimum of genuine Apple stuff installed by the OS.

If you get problems, then I don't know what could be the cause (possibly a hardware fault that has only emerged when M.Lion was installed). If there are no problems, add stuff one by one such as setting up a couple of email accounts, test intensively after each addition for a couple of days, and carry on until the fault re-appears.

I know that this will take ages to do, and I had 9 months of agony in Lion, but in your state I think it is the only remedy. You must find what is causing the problem. Good luck.

Perhaps Thomas Reed could comment.