I have a problem. Today I was riding (flat-out) up hill, and went to shift up a gear on the rear, which caused the chain to drop off the front chain-ring (was in the big-ring, so dropped to the outside). (For reference, road bike with Shimano 105, 52/39 and 25/12)
Throughout the ride it dropped a few more times - generally under some form of load. I noticed that it wasn't always dropping off the big chain ring. Occasionally when taking off from lights (in the little ring), when I stood up to get going, the chain would fall off the front chain ring, to the inside.
Is it possible this is anything other than incorrect limit screws? Maybe something out of:
Chain problem (stiff link? But looks OK)
Chain-ring worn (this is on a ~4 year old road bike, maybe 25,000km without chaning front chain rings, but they don't have the 'shark-tooth' pattern)
Edit: Here is a look at the chainring