Since you have a european PS2, putting a NTSC game in and playing it makes the PS2 output PAL60, which is PAL at 60 Hz frequency. Your problem is that your TV is too old/low quality* and doesn't support 60 Hz, and no adapter will help. You <i>need</i> a TV/monitor that is PAL60 compatible to see the colors.

*(my brother still uses our 16 year old 14" TV set that supports 60Hz)