Tried to install OS X Disc 1 (which I believe was of 10.5 Leopard)
Here is what I did whilst running on Lion on my mid 2009 MPB:
The firmware has been altered as not to boot from 10.5 anymore.
my computer crashed. I can't recover it. The hear the chim when it switches on but the screen is perminently white with no graphic or loading icon.
Run through these User Tips