are your dropouts slightly more horizontal than vertical? they are on my bike, and when i got it it had Campy skewers that had a small acorn with small grooves in it. if the cam wasn't cranked down super hard, the wheel would come out under torque with the same results...wheel slammed into stays, me over the bars.

i solved this issue simply by getting a Shimano skewer for about 10 bucks...bigger acorn, deeper grooves, no more slippage.