Look at this thread: "Interpreting PI/PO error scans" for a detailed discussion. Also the "great KProbe thread" somewhere gives valuable information.
Rule of thumb: PI Error should not exceed 280 for a longer time. PI Failures is what will be used to computer the Quality Index in Nero CD DVD Speed. PO Failures (Parity Outer) should not happen at all! IIRC those are Failures the Error correction cannot correct anymore, while PI Errors (Parity Inner) are corrected by PI and PI Failures are corrected by PO. You will find errors even on the pressed DVDs, even CDs. Floppy disks with their low data density use ECC as well, same with hdds - you just cannot measure them (only if they fail). hdds may give some info about them in the SMART data, AFAIK. This is not an exact explanation - read those recommended threads to learn more
But: I dont know what PS2 disc you copied and with what software. If you used a great copying tool (for copy-protected games, e.g.) it may be it copied defective sectors from the source disc! You may want to scan the source disc with CD DVD Speed, DVDInfo Pro or KProbe - maybe these PO Failures were copied 1:1 from it. I cannot tell you for sure as I only do backups.
Normally I would consider Verbatim (do you mean MCC 003? mo3 I havent seen so far...) a good and reliable media. But maybe "mo3" is some cheaper stuff Verbatim sells under his good brank name - guess you would see more complaints about them soon! Ricohjpn01 I havent had so far, too, but many ppl here are very satisfied with them, so if they are better, dont wonder.