I have a 1633s Liteon, had it for about half a year now, burnt tonnes of dark purple ritek/ridata discs, and a whole bunch os Sony and Verbatum DVDRWs.
This weekend, picked up some light burple onindtech media, and could not burn any of them, so figured maybe the media was garbage.
Purchased a few spindles of TYG02 media:
these discs are also light purple on the data side, and I cannot burn ANY, at 4x, while everyone else seems to burn these at up to 12x easy.
lol PI scan:
(couldn't even finish the scan, would not get passed 34%, just made annoying loud noises trying to spin the disc up and sub luminal speeds.