I just went over to my DVD player and ejected the last Dual layer disc I tried to burn that won't play. I put it in my Laptop internal DVD player/write..and I'll be darned, it started playing.
well you pretty much just proved the software aint at fault as the backup's worked.
but i do believe Liteon makes a program that allows you to permanently change the booktype for DVD+R DL to DVD-ROM. OR (if you want a simple way)... i think ImgBurn allows you to change it from it's software "Tools > Drive > Change Booktype" then select LITEON and change accordingly ... then any DVD+R DL discs (etc) you burn in the future should have DVD-ROM for the booktype after the burn is finished.
but my guess is that your using low quality media is why it's not playing (but if you got a older DVD Player. it's a good idea to change the booktype as i said above). odds are Verbatim will work almost for sure since it's the best QUALITY DVD+R DL discs you can get.)
in fact, i believe you can check to see what the current booktype is set to by sticking that already burned disc into your laptop burner etc and load up ImgBurn and it will show what the current booktype is set on those burned discs. you can check it by doing this...
stick in the burned disc, load up imgburn. put imgburn into "MODE > READ" then select the drive that the disc is in and after it reads it you will see on the right hand side of the program a whole bunch of info... scroll down to where it says something like "Physical Format Information (Last Recorded - L0):" and just below that you will see "Book Type: DVD-ROM" (your's will either say DVD-ROM or DVD+R DL) .... it's best to have DVD-ROM.
p.s. but as far as your current (low quality, most likely) media the best thing i can suggest is try lowering the burn speed, especially if your burning those discs @ 8x. but if 4x fails, try 2.4x. if 2.4x still dont work there's probably not much you can do besides getting better quality media. OR if you have another dvd burner you can try that to. but i figure it's mostly the low quality discs that are the issue because even if they worked on another burner and dont work on your Liteon drive that don't mean your liteon is a bad burner.