i am no pro, but it looks like maybe when you were vegging, they were too far from the light. I try to keep my fluoros within 4 inches from the tops.

also, i think you had temps that were way too high as well. i am currently building a simular cab. i will be using a 400w hps as well, but with a cool tube. I freak out when my temps hit 80! hehe. I try my best to keep it right at 70-75.