NTSC PSX Backups on PS2

Geforce (25-07-2001 11:14):
Right guys i need help/advice, I`v ejust purchased a UK PS2 with mod chip fitted.. Got it home and tried to play my psx backups, UK Backups worked fine but all NTSC Backups stopped dead and did nothing.. Is there a problem booting NTSC backups on UK Ps2 if so how do i combat this so i can play them.. Even Games that have the NTSC/PAL Switch won`t boot.. Any help u can give will help me a lot..

I`ve had a quick look for a ps2 boot disc but can`t find one so i presume there isn`t one yet?

I've tried to think this one through. The system should, for playing purposes, be oblivious to PAL/NTSC once you've got past the boot sequence using a PAL PS1 original. The worst that should happen with NTSC backups is a greyscale image - and that can be cured.

So what's left? Were the UK & NTSC backups created with the same software on the same equipment? i.e. there is nothing duff about the NTSC backups?

Or are you NOT booting with a PAL PS1 original before putting in your NTSC backups?