From the SA2 glitches guide (ignore that it says SA2B): Given GD-ROM's are non-rewritable, I don't see how that could possibly happen from just a Gameshark code. My guess is that the writer of that guide somehow mishandled the SA2 disc as he put it in the Dreamcast, and unwittingly damaged it in the process, resulting in the issues he encountered. But I'm still real curious; maybe there's something I'm missing? Does anyone else remember ever trying this, whether you saw it in the guide or not? If so, what happened, if anything? I feel like I might have made a thread or post about this here a long time ago, but I tried both Google and the forum's own search and can't find it, so I think I'm more likely misremembering. Sorry if I did!
I also can't imagine this caused permanent damage to his copy of SA2. Perhaps it corrupted the save file in such a way to cause these issues? Only thing I can imagine, besides what you already mentioned.
It's possible for the Dreamcast itself to get messed up as some stuff is stored in writable flash such as internet and systems settings. However if that happens it might be possible to hard reset that back to factory and removing the battery won't fix screwed up system settings.
Okay, this sounds eerily similar to an issue I had years ago, I completely forgot until now. Once upon a time I was playing some casual SA1, watching the cutscenes before the Perfect Chaos fight. My friend is nearby and he accidentally knocks something over and there's a fall. No biggie, except the vibration from the tumble caused the Dreamcast to briefly freeze/skip at one point during the pre-boss talking. I can't remember exactly what happened but there was definitely a reaction from the Dreamcast/Game caused by the vibration. Strange thing is, from that point onwards, the same thing would happen whenever I reached that very same moment in the game. It acted like it did when the console was briefly shook by vibrations. Like it was somehow now stored in the console memory? It was weird and I never looked into it. But I wonder if this SA2 sound glitch has a similar reaction? Something stored in the console's memory that triggers abnormally for some reason?
That bug where the music stutters as the screen fades white before Tikal appears? It happens in all versions of the game on every version and make of the Dreamcast I've ever used. The first time through it might be a slight stutter where the second time through it's a more pronounce stutter. Cause? Buffer under run. The Dreamcast is not super consistent in those contexts. Or does this occur at a different point from the normal situation?
I don't feel like doing the research to prove this claim, (sorry) but the odds of the SA1 debug code causing SA2 to write to flash rom are extremely low if not completely zero. The SA1 debug code writes 00000000 to an address in memory. Outside of maybe reading some system settings like language, SA2 itself has no reason to write to flashrom and zeroing out a single address in memory isn't going to cause code that doesn't exist to write to flashrom to write something that would cause problems with a single game. Games are allowed to write some data into Flashrom themselves, but SA2 does not. I looked at a dump from my own DC just now to verify at least that much. The on-disc web browser reads and writes internet settings from flashrom, but Gameshark codes will not persist when switching to the browser because it loads a completely different executable for the browser blowing away Gameshark's hooks. (This is why if you switch to browser and exit back to game codes are also lost) Even if you accidentally corrupted flashrom, I doubt there would be problems. There are free tools to intentionally erase a Dreamcast's flashrom which people have used to wipe their Phantasy Star Online access keys in order to use different ones. Also, Dreamcast emulators seem to work fine starting from scratch with a completely empty flashrom at first boot. I'm going to agree this story sounds very unlikely and was probably a coincidence.
That would indict a corrupted save file in that case, this is assuming of course that the game didn't really glitch in a bad way and write something somewhere it should not have to the system itself. Who knows? Could try it out as I got a few extra memory cards and a Game Shark for my Dreamcast but it could be like a lot of other stuff on the web in that it's says it affects the Dreamcast version but in reality it affects the GameCube version instead or was a total coincidence or possibly a fake message to scare people. I have a GameCube and a copy of SA2:B for it but no GameShark for it nor do I have an extra memory card for it either.
Update: So I tried it out and nothing happened with my copy of Sonic Adventure 2 for the Dreamcast. Of course randomly writing crap to parts of a game's memory could cause problems with any game, so I wouldn't advise you do that. No audio glitches occured. So either two possibilities exist: the guide is bullshitting you or the conditions and the exact code that was used was not documented. That guide is from 2002 and the author of that is probably no longer around.
There was no GameShark for Gamecube, which completely rules out your suggestion. The GameShark brand name means it had to be Dreamcast. Interact partnered with Datel to sell their Action Replay devices in the US under the GameShark brand name in the late 90's and 2000. Datel terminated their partnership with Interact around 2001 and by the time Datel developed the Gamecube Action Replay they sold it directly in the US themselves under the original name and had established an office in Florida responsible for handling codes for US games and also their online store. I used to hack unofficial Gamecube Action Replay codes, and sometimes chatted with one of their employees via IM.
