why do i have to reburn games

[med]

i recently got my ps2 chipped (neo 4).i have downloaded a lot of games most of which i burned with fireburner, a few with clone and easy cd 5. problem is that hardly any of them worked .
all looked ok when exploring the cd but they wouldnt boot (some would after about 5-10 retries . (all backups from originals done with clone work sound.)
i then tried reburning using clone and they all work straight away ,every time.
does the ps2 not like games used with fireburner ? should i use cd-r win ? last time i used it, it was burning blank cd's, then someone said use fireburner which worked sound with pc iso's.
also can anyone tell me why some psx games are recognised as audio cd's?
thanks