Today I was taking some pictures with my 7D and 70-200mm lens, and everything was fine. Then I switched to a 17-55mm and for some reason it wouldn't take a picture. Everything else works. It focuses, I can view images stored, it switches modes, the flash pops up in auto-mode, etc. But when I depress the shutter release (it will focus) but not take a picture.
I've tried recharging the battery (it was low) switching CF cards, and clearing all custom functions and nothing worked. The lock switch on the big wheel doesn't affect it either.
For some background, I'm in Afghanistan and it's been extremely dusty. The camera isn't what I'd considered abused, but it's well used, certainly a bit dirty, and gets some rough handling at times. The mode switch has always been sticky. When I turn the power lever on, the mode switch tends to change functions too. Usually from my normal Av selection, to Manual. But as I mentioned, the mode switch does work, as well as the power switch.
I'm wide open for suggestions, and am not above trying field repairs at this point. It would take over a month to ship it back, get it fixed, and then shipped back. I'd probably buy another body in the mean time.
Thanks for any help.