[RM2K3] WRONG AUDIO SOMETIMES PLAYS FOR CERTAIN ANIMATIONS

I made a game with all unique assets for a game jam in october. I'm developing on my main PC which runs Windows 7, and everything is working as intended in testing.

However, I had somebody do some playtesting on Windows 10, and every time any spell that uses the Buff or Debuff animation was cast, it would play such a sound from the RTP rather than the imported sound file that is inserted in the animation.
I have since tested on my old Windows XP laptop, and the same audio errors happened consistently.
(I don't necessarily think the problem is with the OS, but these are the different environments I've been able to test with.)

I've extracted the same archive to a separate folder on my Win7 PC, but I can't replicate the problem. As such I don't even know where to begin attempting a fix. Everything looks fine in the engine.

And I think it was just the Buff & Debuff animations. I think my custom Heal, Damage, and Magic Damage animations worked as intended all around. As do all other custom assets.

I would really appreciate any and all insight. If you'd like to help test, I'd be most grateful.

Here's the game disc, as made by the Steam version of RM2K3
And here's a save where each character has a buff/debuff
All you'd have to do is walk around, get into a random encounter, and cast Speed Up and Defend Down. If they play buff.wav and debuff.wav, great! If they play anything else like Down.wav, there's a problem and I wanna be able to fix it.

author=LordBlueRogue
It might have something to do with RTP not being installed correctly on later operating systems, maybe?

Holy crumbs, that's totally it!
What I'm discovering now is that every install on all my available PCs that go through Setup.exe have the RTP audio error, while every install on those same PCs that are just extracted straight through the .lzh play the correct audio!

Setup.exe is the culprit. And now that I know that and I didn't do anything wrong in the engine, I'll just make the game available without it.

Thank you so much for pointing me in the right direction!