make sure that you don't use a dvd-RW at all. try to use dvd+ (plus type) instead of the minus type. slim consoles are more compatible with the plus type rather than with the minus type or at least this is what i've read before.
IMGburn or dvd decrypter are your best burn softwares to use. if your burner is an older one then i'd that you burn at a slow speed or med speed if possible for best results.
PS1/SCPH-7501 | MM3 modchip
PS2 v9 | 250GB hdd | PS3 component cable | katana 32mb mc
PS3/CECH-2001B | 250GB hdd | 3.65 ofw