Len, thanks for the reply! The Sunpak DF3000N (Search B&H Photo) is a 'Idiot flash' - no controls at all on it, except for power, fully auto TTL settings:) We do mostly studio work with wireless triggers, so a 'flash' isn't a biggie for us at the moment since we're still on the fence with this camera.
The problem I'm having is when I turn the flash OFF (by the flash's power switch) and it's still attached to the camera, (and the pop-up flash is closed) the camera doesn't see that I turned the flash off and still has the 'will flash' icon on the display. By turning the flash off and the camera expecting it to fire, it doesn't allow a photo to be taken.
In studio, with the wireless trigger attached instead of a flash, I have to physically remove the trigger since the camera doesn't have a 'no-flash' setting, if I don't want it to fire.
Any mode, P/S/A/M - if I have either the flash or the trigger attached, if I remove it and the camera is expecting it to flash because of low-light, I get locked out. Make's it really hard to do dark shots.
Now, on the other hand, not comparing apples to oranges, with any of the Sony Alpha's, I set shutter speed and aperture, tell it no-flash and start shooting.
Ive spent more time trying to figure out what's going on with the D5100 and the flash issue then I really wanted to. Why can't nikon just give us a 'no-flash' option in the settings and be done with it :) LOL