A weird one that happens in both PS CS4 & CS5, 100% consistently:
When more than one document with at least one non-background layer is open, the amount of a *changed* opacity field value in the current document is also applied to a *selected* non-background layer of the next document if Ctrl-Tab is pressed to go to the next document (or to the Previous document if Shift-Ctrl-Tab is used to go to the Previous) while the Opacity field still has post-update focus. (To avoid, press Enter or otherwise exit the *updated* Opacity field before pressing Ctrl-Tab or Shift-Ctrl-Tab to go to another document.)
In CS4 even a background layer is auto-converted to a non-background layer prior to applying the value from the previous document's updated Opacity field.
In CS5, if the secondary document has *multiple layers* and the background layer is selected in the secondary document, pressing Ctrl-Tab or Shift-Ctrl-Tab to go to the secondary document from a primary document post-Opacity-change causes an immediate Windows 7 APPCRASH event, closing PS due to a 0xc0000005 access violation.
The same behavior occurs for the Fill field.
All of the above is completely repeatable.
I can't imagine this having to do with the graphics card, as I don't believe it's a graphics issue.
The issue is not that the secondary document's selected layer is merely "displayed" at the primary document's opacity value. The issue is that the opacity *value* is actually *changed* (field value) for the secondary document's selected layer to match the primary document opacity change. (Or worse, APPCRASH under specific conditions described, photoshop.exe the offending module.)
My system has a supported graphics card (ATI Radeon HD 4850 - 512mb) which works fine with all OpenGL acceleration features that I've tried. ...Robust, relatively new Win7 x64 system with plenty CPU/memory/HD/power-supply,etc...
Please try to replicate the very specific condition detailed in my post - it doesn't take long to set up.
Never mind my previous comment. I was able to reproduce the behavior you reported, though I haven't seen a crash (with CS5 12.0.3).
There's an Adobe bug report form here:
Thank you very much, Noel, for taking the time to replicate this quirk. I'll report this issue using your form link.
To summarize, (more details in the original post), when Ctrl-Tab or Ctrl-Tab-Shift is used (to go to another open document) while post-update-focus is still in effect on the Opacity or Fill fields, Photoshop apparently tries to apply the Opacity/Fill field value from the 1st document to the second document's selected layer.
It took a long time (and multiple versions of Photoshop) before I ever triggered this issue, but in a particular situation where I was comparing/updating multiple versions of a layered document, I ran into this frequently and hair-pullingly!