Today I upgraded from MacOSX 10.5.8 to 10.6.3.
And I was working in Photoshop CS4. Not sure if this is related to the Snow Leopard upgrade, but...
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“About Photoshop” is greyed out. Can’t tell what version I have.
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The LAYER, CHANNELS, and PATH palettes have all options greyed out, except “Convert to smart object”, (don’t know what that does).

QUIT in Photoshop is greyed out. Have to Force Quit.

On another forum I was told to delete Photoshop CS4 Settings folder in Library/Preferences. Which I did. Then relaunched. It works for a few minutes. The Settings folder comes back, of course. Then menu options are greyed out again. I think it starts at the first SAVE.

How to fix this? Is this a Snow Leopard conflict?

There were definitely some updates for CS4 when Snow Leopard came out. Did you check if CS4 has any available updates since upgrading your OS?

And... 10.6.3. Update to 10.6.8 + all updates and then update CS4 as well as necessary. CS4 supports Snow Leopard.

Yes, I've done both - Photoshop 11.02 and OSX10.6.8.
When I Force Quit, I can get out of Photoshop. After relaunch, it works until the first SAVE.
Haven't been able to find any solutions. As a designer, it creates huge problems for my workload!