Can't start up from 10.5 Install Disk, but can from MB Pro Install Disk?

Question

Many thanks in advance for your attention.
1. I was going to Verify (and then maybe Repair) HD by starting up my computer from the OS 10.5 install disk, but my laptop just blacked out (froze) each time I tried to start up from the 10.5 install disk. I tried starting up holding down the "c" key, the "option" key, and the "shift" key.
Each time my laptop just blacked out and froze. Odd as the 10.5 install disk has very rarely ben used and has no visible scratches, etc. I think I haven't used it since the original install.
2. So I tried instead the original Install Disk 1 that came factory specific with the MacBook Pro (which also has 10.5 and iLife, etc. on it). Held down the "c" key and I was able to boot from the Disk (and do a Verify Disk, etc.). No problems at all.
Anyone know what could be up with my OS 10.5 Install Disk? Is there a way to test if the Disk itself is somehow damaged?
Thank you.

Answer 1

Thanks again for your response.
I am all for these forums in helping people out. I know some questions/ answers can't be all black and white.
But - in the interests of clarity for others out there -
1. Again, I was not trying to INSTALL from the 10.5 Install Disk.
2. I was merely trying to insert it and use it to VERIFY my HD.
3. I know one cannot do an "update" INSTALL from (for example) a 10.4 Disk if one already has 10.5 installed.
4. But - through the incarnations of 10.1, 10.2, 10.3, 10.4 - I had always been able to use the OS X retail install disk (no matter how old) to check out my HD, even if my HD had (for example) 10.3.5 on it and my Install Disk was just 10.3.
According to the link William posted, this may be different (I would guess on rare occasions), starting with Leopard.
5. But, given my history through all the incarnations of OS X, I was puzzled when it seemed my laptop could not read my very unused, mint 10.5 OS Install Disk. A mystery. But when I washed a seemingly flawless disk, it worked afterwards. So something must have been on it I couldn't see.