Minimizing or switching to windowed cause a blank screen

I've just returned to CoH after a break of several months, and I find that now when I switch from windowed mode back to full-screen by using command-return, or minimize the game via command-tab then switch back to it, my screen blanks out. The screen seems to be a random color, there is still sound in the background, and the keyboard is still responsive, but the entire screen including the UI and cursor blank out. Moving around will cause the color to change and I can hear movement sounds, but the screen will remain a solid color. Switching back to windowed mode puts everything back to normal, but going back to fullscreen causes the problem again.

The problem only occurs on 3D screens. For example, I can switch on loading screens, the login screen, the server selection screen, or even while displaying my characters ID card without encountering the problem. But any time I switch while in game or on the character selection screen, the problem happens. Switching to windowed mode on a 3D screen, then back to the game on a 2D screen will cause the problem. Switching to windowed mode on a 2D screen, then to full on a 3D screen also causes the problem. While switching to windowed mode then back to fullscreen on a 2D screen does not cause the problem, switching out on 2D, then switching to a 3D screen, then back to a 2D screen before switching back to fullscreen mode still causes the problem. If at any point I display a 3D image while in windowed mode or minimized, my screen will go blank when switching to fullscreen.

I hope that's clear enough; I tried every combination I could think of for switching to windowed mode or minimizing then going back to fullscreen to try and narrow the problem down.

The problem persists when I start in safe mode. The problem persists after re-downloading and installing the client.

I've used both versions 3068 and 4462 of the Mac client, but I wasn't playing for about 3 months before issue 20, so I couldn't say exactly when the problem was introduced.

System Profile:
iMac (iMac 7,1)
OS X 10.6.7
Intel Core 2 Duo 2.8GHz
4 GB RAM
ATI Radeon HD 2600 Pro, 256 MB VRAM

The problem is kind of a nuisance, but I can work around it by just leaving my character's ID card displayed whenever I need to minimize the game for a bit.

Click on the CoH application and use the Get Info command in the Finder's File menu - which version do you have?

I have passed this problem along to tech support while discussing the current "i20 broke the game for newer macs" issue. It has been going on since at least i19. Send tickets to tech support, just in case. Would love to be able to window in and out without quitting the game.