I have a Mid-2010 MacBook Pro which one year ago I upgraded from the default Snow Leopard to Mountain Lion. However, now I want to downgrade to Snow Leopard again.
I made a USB thumb drive formatted as MacOS (External Journaled) to install Snow Leopard again (my CD drive doesn't work, that's why I made the USB flash drive).
Anyway, when I'm trying to boot from the USB drive with the Option key and press the MacOS Install DVD icon, it gets stuck on the Apple logo forever.
My question is, do I have to first erase Mountain Lion completely and then try installing from the USB drive or is this a kind of a hardware problem? I'm thinking of formatting my hard disk but I'm scared of the Apple logo getting stuck again.