PS2 DVD weirdness?

So I went and made a backup of twisted metal black and onimusha: warlords because they were starting to show their age. Anyway - I used DVD decrypter to make the isos and then I burned them to sony brand dvds. I burned the isos and went to test the copies but here's the odd thing - the games didn't load properly. cinematics were choppy (as if the disc was scratched or like when you try to play an avi file when running 2 instances of doom 3. Load times were also screwy - taking like 3x longer than normal. In game was normal because its not dependent on the DVD but sound was affected occasionaly - again as if the ps2's laser was having trouble reading the disc.

my question: does this indicate that the DVDs used aren't suitable for                                burning or is there a problem with the isos I created  ~thnx in advance

-slim ps2 (about 6 months old)
-swap magic 3.6
-DVD's used: Sony DVD+R with "accucore"
-backups on other brands work (I verified again)

Yeah; thats happened to me with a few burned games+swapdisk. Your best bet is to use a lower speed when burning, and to make sure you have the disk in the tray properly.

I wish I could... 4x is as low as it goes, but I'll try another brand - just wanted to make sure it wasn't my burner or the isos.