Hi, Bridge Command 4.x was set up for standard 4:3 ratio monitors (e.g. 1024x768), and doesn't work well with wide screen ratios. The next version (5.0) will work fully with wide screen monitors.
I'm not sure why you are getting problems with 1600x1200 full screen. Can you try full screen at 1024x768, then 1600x1200?
There's also another option:
In addition to the normal graphics mode of full screen (graphics_mode=1) and windowed (graphics_mode=2), there's a special mode for 'windowed with no border' that you could try (graphics_mode=3).
To get a display at 1600x1200, if your screen supports this, try the following:
Make sure you're on the latest version (4.7, just released)
In Windows set your screen resolution to 1600x1200
In the bc4.ini file, set the graphics width, height to 1600x1200, and set graphics_mode=3.
Bridge Command should now start covering the whole screen (but actually in a windowed mode). If necessary, hide the taskbar.
Let me know any success.