Has anyone found a compatability list of DVD-R media for apple superdrives......I bought some SONY DVD-R 4.7 GB from wal-mart but so far all have been coasters, even at 1x. The blanks i bought were sony "DMR47L1"

I have a imac 17in g4 1.0 the superdrive listed in my profiler is: DVD RW DW-U10A "SONY"