i bought a macbook pro 2008 a few days ago and it had el capitan on it, but i wanted to install snow leopard on it so i inserted the disc, swicthed it back on holding C and done the usual disk utility erase and install, everything fine till i noticed its taking a little longer than usual then i got this on my screen (attached photo) anyone know what to do? i already put a new hard drive in their and its the same thing 