[spooky]

Well there are issues with the plug mod and most would recommend an internal mod chip (But each one has pro's and con's). Plug mod's may not work with some games and can affect other in different ways, such as memory card problems, but i find it hard to believe that 4 out of 5 games refused to load!

There are many other reasons reasons for this, the burner, the media, the recording software, the recording speed, the system set up and even the psx itself, but you said that all you other backups work fine so its probably not your PSX.

Looks like you've been a victim of shoddy workman ship!