Hi there BMS.

I think the problem lies with you having some n-gon polys on your mesh there - the conversion to sub-d won't be very clean unless you try to keep to 4 (or 3 if you have to) sided polys. I think the edges that I've pointed out in red might be causing the problem, you could clean up these edges by splitting the mesh where I've shown in blue, but I'm no expert, so I don't know if that will get rid of the creases.

Hope it helps a bit anyway, keep up the good work

LisaG