Matt Laur , Jul 05, 2009; 08:48 a.m.
Just to be sure on one thing, Daniel: do you have the camera body's front function button set up to trigger the modeling light feature? If your way of gripping the body leaves your right-hand finger tips grazing that button, you could easily be firing off the modeling feature, which looks just like a flickering strobe (because it is a flickering strobe!). If that's the case, it a feature, not a bug. And you can turn it off.