Running Photoshop CS5 on Win7, both 64 bit. No problems for months, then recently this minor "annoyance" appeared.
I "host" ACR via Bridge, with the windows for all three apps maximized. I double-click a raw file in Bridge and ACR opens. I make my ACR adjustments, or not, and click "Open Image" to pass to Photoshop.
The images passes into Photoshop OK, but the Photoshop window does not receive "focus". Instead, the ACR window closes, leaving the underlying Bridge window displayed. But then no window has focus.
When I click once on the Photoshop tab, I get a screen flicker, like a window is being minimized, but the Bridge window remains displayed. I click again on the Photoshop tab and it comes up, full screen with focus.
If I take the ACR window out of "maximized" mode, the problem does not occur. Raw images pass from Bridge through ACR to Photoshop with proper window focus. Opening tif, psd, or jpeg images via Bridge is no problem. Only when raw images pass through a maximized ACR window does Photoshop fail to receive focus.
A few days ago I used the Windows 7 "snap" feature to place the Photoshop window and ACR window side-by-side. This is done by dragging a window off-screen until it turns blue and then releasing. I believe this action caused the problem I'm having now. I've unsnapped, resnapped, and unsnapped the Photoshop and ACR windows several times, hoping to clear the problem, but it remains.
Keeping the ACR window out of maximized mode is an easy work around, but the mystery remains and I hate mysteries.
I know how you feel, I've had a few problems like this with CS5. I can only think of two suggestions:
1. Disable Windows 7's fancy desktop (Aero peek, or whatever it's called) to see if that helps.
2. Make sure you're sorting by filename in Bridge. I have noticed that sorting by metadata causes Bridge to sometimes steal focus when it's not wanted. I love Bridge, but christ it needs a good sorting out.