Are you riding along and then the tail whips out of the water?
If so, then it could be two things: 1. pointing and 2. edging. (Think: 1. dragging a board across the water at right angles to the movement - doesn't really go forward smoothly and easily pops out and you fall on your bum and 2. dragging the board flatter across the water - doesn't carve well and pops out, then digs the downwind edge in)
So try:
1. pointing / looking at somewhere less upwind. You need to adjust your pointing for the surface conditions (swell - up the wave and down the wave / chop) - ease up going up the wave on your way back to shore (Perth seabreeze conditions).
2. Also if not already doing this - push your hips forward and lean back more on your harness (avoid the poo stance), AND keep your front leg straighter and back knee bent: these adjustments allow a better transfer of the kite pull (cross-downwind) through you, to the rear half board edge (cross-upwind).
Did that make sense or help????


If you've fallen in, board still on with your head slightly downwind of feet, try moving the kite to the edge of the window (feet side). Then lift your board and legs out of the water, towards your lines, by lying on your back and stabilising against the harness / lines / kite and also using your arms a little.
When you are facing your lines / kite the right way, drop the kite towards the other side and power up / ride off!!

Works for me anyway!