Light burn.
You put your youngin under too strong of a light after having it under a weak one or none at all. Most plants need a lot of light but for some reason if you add it too quickly they shrivel up, dry up and die. Lost 12 babies to that bullshit light disease lol.. (thas what i call it)
Use CFL's to vegetate. I use 60w(100w equiv) 6500k bulbs to vegetate (cfl twist) , and to flower 100w(300w equiv) tcp spring light 2500k.
I would just say use cfls to veg then when they nice and healthy move them to the HPS/MH