Please Help Me...

[Shpitz]

I have a problem with my PS2 V4 Pal.
I have a Messiah mod-chip, and this is my problem:
Music discs are working , PSX imports are working but PS2 imports and originals are working rarely. It usually take the PS2 few seconds to recognize the PS2 disc and then there is a black screen with white words:"Insert Disc".
What should I do ?

Thanks.