Ok, here are the symptoms,
1) The camera is not always "firing" when I push the trigger (i.e. nothing happens)
2) This seems to have started with in the last week
3) I believe this is only happening in low-light situations, yet in conditions I would expect to be able to photograph, and have captured in the past.
4) This happens in all modes
5) This is not lens specific
6) This happens even if I bump up the ISO as high as it can go and shoot at f/4 (my limit with the lenses I have)
7) I receive no error nor the usual indicators you would expect when the sensor can't handle the lighting conditions. In fact, the light meter is where it should be and the focus point indicators beep indicating the image is in focus.
Any thoughts are appreciated.