Life Was Good with 8x Dvd-R



yesterday i bought 16x dvd-r (50 Pack)…previously i had burned the same companies (50 Dvd-r pack) but 8X…with no serious problem then usual.
But now when i burn with nero no problem but verified and completed with 8x speed on my sony DRU-830 A…the problem is that cant open the Dvd’s after burning it, the drives behaves like the dvd is scratched …(ITS brand new)but when i put the same burned dvd on another pc it opens, its plays all the video files with no problem.
Plz guide me should i keep these burned DVD’s… its like 50/50
i download a lot from torrents but i cant keep all that data on my drive need to back it up…could some guide me in trouble shooting this annoying problem…DVD’s cost money ppl!