can incorrect window framing (The wood blocks around the window) be the cause of water leak?

I've been trying to understand how my window leaks when it rains. The odd thing is it only leaks sometimes.. not everytime it rains. I've had the siding checked, roof, gutters.. they're all fine. So the only thing I can think of now is the actual window. I have a large picture window with a palladium half circle window above that. It leaks right where the circle window and the large picture window meet but only one one corner and not the other corner where they meet. The only difference I can see from both sides now that I have my drywall pulled down to the frame is on the corner where it leaks, the vertical wood block that meets perpendicular to the horizontal block is nailed at a slight angle meaning it doesn't meet flush, the outermost side of the block is kind of tilted inward or down. Hard to explain, but could this be the cause of my leak? Maybe if it was flush and not tilted inward the water would not get trapped and leak? Any hoome builders in here have a clue? When the water leaks, it soaks up the corner of the drywall where the two windows meet and then water drips down the cracks of the window frame where the picture window meets with the window to the right of that. Again hard to explain, I can email someone a picture if you are willing to help me out.