MBP Boots with 3 POST Tones - Only with CD in drive?

Question

I think I am having an issue with my Optical Drive so it seems - just wanted to see if anyone else has some information on this.
My MBP 8,2 will boot to Lion successfully with no problem. I've been trying to downgrade back to Snow Leopard, after some kernel panics with the original SL disk I purchased for my old 4,1 - the Apple Support crew were puzzled and decided to send me a replacement copy of SL. (As I was trying to boot to disc, I would kernel panic with Lion installed and with NO operating system installed). I received my new SL replacement disk today, and I was overjoyed at the wonderful opportunity ahead of me to downgrade. Except...this time I was greeted with POST beeps. 3 beeps every few seconds. I see that is typically a RAM issue, so I called up Apple again and they once again were puzzled greatly by this problem. Awhile back, I created a backup drive with SL on it - plugged that in and tried to boot to disc, that also resulted in a kernel panic...which is making me think this is something greater than just the optical drive. I've made an appointment to take in my MBP to the Genius bar to see if there is something wrong with my Optical Drive. So basically one SL disc kernel panics, the other one POST beeps.
Now, here is another interesting question. I received this MBP 8,2 with NO install discs. Long story short, I only have the install discs from my 4,1. I received my 8,2 as a replacement from my 4,1 for free with a brand new warranty (had major failures with my 4,1 to bring them to replace the entire machine - buy the warranty folks!). I am looking for the MBP install discs that I used to have with my old 4,1 so I can run the Apple Hardware Test to see if perhaps on my own I can find something wrong - however I know the discs are usually MBP specific. If/when I find these discs - do you think I can use that AHT version for this new MBP? I found my sibling's 13 MBP install discs, but that would be a last resort attempt since it's for the 13 inch. I'm also assuming that my optical drive will co-operate enough for me to run it.
Anyone else in this kind of bizarre situation or has any recommendations for me? I realize I am going to the Genius Bar on Sunday - but I like to do a lot of my own testing and see what happens on my own. (Just because I've had a bad experience with one Genius Bar visit on my old 4,1).

Answer 1

Lucky for me I found (to where I thought I didn't receive them) the 15 inch MBP discs. I must have traded my old discs for the newer ones. And of course, I was able to get to the AHT and the Mac OS X 10.6 install screens. I think what happened is that I was putting in retail SL discs that were originally purchased for my laptop that was running Leopard in the first place. So I am guessing that my current MBP (pre-loaded) realized that those were not the proper discs, and that I should have been using the install discs (the grey ones) the entire time. Funny that none of the advisors over the phone recognized this either, even when they asked me what was pre-loaded on this machine and what type of disc I was using (I specifically explained I was using the disc I pre-ordered when Snow Leopard came out).
So I am now wondering, if the beeps with the retail version disc of SL were related. Because other than that, the machine boots flawlessly with the correct discs and without the discs, no POST beeps. I ran the quick AHT test, didn't indicate anything - but I will run the full one later.
I'm trying to think now if it is worth running into the store to have them look at the machine, because I think I localized the problem - putting incorrect discs into the machine and trying to get it to run. Might call them again tomorrow to see what they think (just because going to the Apple Store is really out of my way).