i have a d90 and i was at a shoot the other night. i was using the built in flash to trigger my strobes and about halfway through with pretty quick firing it would not shoot, id hear the autofocus beep but nothing. i figured its either my flash was too hot to fire or the pictures werent getting written to the card fast enough. it would work again for another 4 or 5 frames after i let it sit for 15-20 seconds. i was shooting raw. what do you guys think the problem is?