Display drivers often have bugs in their OpenGL implementations.

PC users can generally download drivers from the manufacturer of the display interface (e.g., ATI, nVidia, Intel), and they have the capability to upgrade/downgrade just those drivers separately.

As far as I know, Mac users must wait until Apple releases display drivers as part of an OS update.  I'm not sure of the time it takes for them to test and approve new driver updates from the maker of the GPU.

-Noel

It's not to be expected, but your computer system has to work right to support it.  Just because it's a Mac doesn't mean it works right.

Does it work if you turn off OpenGL Drawing in Edit - Preferences - Performance (remembering to restart Photoshop before testing)?

-Noel

I am not bringing up PC vs. Mac for any reason except to say that in this particular case you have less flexibility about mixing and matching OS update levels with display driver releases.  Usually Apple's pre-qualification of drivers helps you keep from having problems, but when they let something through that's less than perfect you have a situation just such as yours, where you're locked in.

I suggest you bug Apple about this particular problem, though, so that they then bug the driver writers to fix it.  No one here can do much about it.  It's pretty clear not everyone using a Mac or PC sees it, and Photoshop's use of OpenGL to do its display gymnastics is generally sound.

Keep in mind that with OpenGL disabled, you have the same basic display update logic in force that Photoshop CS3 used all the time.  This is likely why Adobe left all that functionality in there, selectable by this setting...

-Noel

I ran into the same problem (also on a brand new Mac Powerbook with all the software updates).  The .psd document loads in layers and in the Navigator but not in the workspace. 

Interestingly, it loads just fine on an older desktop iMac running 10.6.8 with the same Photoshop 5.1 version. 

The added problem was that as suggested here, disabling OpenGL Drawing didn't work.  The only thing that did work was stew_graff's suggestion of disabling Automatic graphics switching.  Thanks man!  That's a helpful interim solution...

So how do we most effectively bug Adobe, as this is a user-to-user forum and this problem doesn't generate a bug report?  I shouldn't have to drain my battery to get this to work...

I am aslo experiencing this same issue. My image will not laod but it is visible in my layers pallette.

I'm surprised that Apple would attempt such a "hack" design...  Switching graphics adapters mid-stream is no small task, and I can't imagine that they could ever make it work seamlessly.

Keep in mind that the nature of the complex GPU beast is that graphics hardware doesn't all work the same (or right) and application software has to make decisions about what to do and what not to do, and even when to invoke certain workarounds - or it would never be possible to run on multiple platforms. 

Yes, that seems wrong, but it's necessary and it makes developing cutting-edge graphics applications in the real world much more expensive.

The decisions aren't re-made by an application all the time - that would slow things down terribly.  Instead, often the run-time environment is characterized at application startup and the features remembered for later use.  Modern applications actually even create programs (e.g., shaders or OpenCL programs) to run on specific GPU hardware, and they have to be compiled - something usually done by the application at startup.

Now imagine that someone changes the capabilities of the graphics hardware completely after the application has started - even from one vendor's implementation to another (Intel to nVidia).

Like I said, I'm surprised a reasonable system designer could ever think that swapping GPUs at run-time could be made to work.  At least Apple allows you to turn it off!

Does Apple offer any "geek-level" configuration options that can force the use of a particular GPU for a given application?  It seems that this could be an automated workaround that would allow a given application to see only one GPU, which is what Photoshop appears to need here.

-Noel