Square woes

[Stillquesting]

Ok, people - this one is going to stump you:

I got a PSone (PAL) with a modchip installed. I use a bootdisk (Importplayer 2.0a) to play various backup games and generaly the unit works fine. EXCEPT with a couple of games by Square:

I got the original Final Fantasy IX, which a clueless but well meaning friend got for me in the states (NTSC version...). Obviously, it needs the bootdisk in order to run well on my PAL machine. The game starts out fine, but freezes the moment I try activating any of the (!) or (?) hotspots with Vivi in the first city. The game works fine on my PC emulator. I thought it was some sort of nefarious regional protection scheme unique to this game, then a couple of days ago I got the Final Fantasy Tactics (NTSC)ISO from the net. The game works fine on my emulator, but after burning it and trying it on my PSone, I encountered a distressingly familiar problem: Game starts out fine, I finish the first combat - But then, when I get to the beginning of the second combat, the game freezes completely.

Ideas, anyone? I searched the net in vain, you're my last hope...