@PowerPie: That's pretty much what I was getting at. I was wondering if maybe (just maybe) you had a **backup** version of Dino Crisis 2 and Keropi had an original and possibly you were at cross purposes.
I'm not sure - it's many years since I last looked into this sort of thing - but I have a feeling that when PS1 games were copied the original boot-sector was lost and the mod-chip ignored this fact and booted the game anyway. So maybe the ORIGINAL has region protection which somehow isn't present on the backup?
I'm sure some clever soul here will know.