No entry sign on MacBook pro when installing snow leopard from 'new' disc onto new HD My HD died on my MacBook pro so I decided to change the HD myself. I didn't have the original snow leopard disc so got a copy from a friend. When I try to boot from disc (holding c) is runs the DVD drive, followed by apple symbol. After a short while, the apple symbol is replaced by a no entry symbol. Totally at a loss as to what to do. Tried different copies of the copied disc, but same issue.

Any thoughts?
Is your friend's Snow Leopard disk one he got with a Mac, or one he purchased at retail?

Disks that came with Macs are hardware-specific, if it came from a different model/revision than your MacBook Pro, then it likely won't work.

Try your install with a retail disk (or a Lion/Mountain Lion installer on USB) and see if that works.