Pal, 10x is too fast. I burn my backups at 4x, and it's only for this one PS1. My other one won't read it, nor the PS2. So I't really up to the lowest burning speed. Try other burners available to you, and diffrent manufacturor of media. My PS1 doesn't like Philips CDs at all, for me the brands that work the best are:
Verbatim -printable (blue-ish bottom disc color )
-Crystal (also blue-ish)
Traxdata - I bought some games from a local pirate seller, and he used this discs:
052.215.029.jpg
They work on all my PS1's and my PS2.
You might want to look for older CD burners with lower burn speeds.
Also, if the game is copy protected you have to patch it.