Cannot boot Leopard Disk

[SlashX]

I am currently running Tiger on my moms Mac, i was trying to upgrade to Leopard, and i put the Disk into my mac, and it says Restart. It restarts boots of the Disk and then the apple logo with the wheel spinning, just spins forever and ever n ever n ever.
Any ideas?

 

[MacDawg]

Is it a retail version or did it come with another computer (gray restore disc)
If it came with another computer, it is specific to that computer

Woof, Woof - Dawg

 

[SlashX]

Retail.