Hello, sorry if this is a repeat topic, hopefully it's not. I have a number of Sonic Adventure games which I purchased together, disc only stacked on a spool, which are mostly in like-new condition. I sold a few on eBay and one customer ended up filing a case saying the disc was defective and that the production number of the disc indicated this. I checked out the other discs from the stack his disc came from and each one had the same production number as his. I tested a number of the discs though each one worked just fine so I then sent the customer a replacement copy assuming that it was just something that might have been wrong with the first disc I sent him. I was then told though that the replacement disc was not working either. The discs all have the number "IFPI 9220" printed on the inner plastic ring, which is mentioned on some sites as being from a defective run of these discs. For further testing, I just tried running one of these discs on a different Dreamcast console, the black Sega Sports model, and it actually didn't boot up, so for some reason the discs work fine on one model console but not the other, and most likely there are a number of other consoles these won't work on since the customer told me he tested the games I sent him on a couple different systems.

My questions basically are, does anyone know why these discs would run on one DC console and not others, and is there any sort of list or way to know what consoles these discs will work on?

Thanks!!