Can USBAdvance run any of those games?
If if can't run those games it SHOULD have been able to run, I think that your games are corrupted.
Also, when you defrag your games(Your disk MUST be defragmented for OPL 0.6 to work), make sure that there are no files that are fragmented(Windows defragmenter may leave some files fragmented).
NOTE: Even 1% file fragmentation is unacceptable to OPL v0.6.
Alternatively, if all else fails... delete and re-create your HDD's partition(And set it to active). Format it as FAT32.
I think that it's quite unlikely you have the same problem as the minority of us(White screen only for all games/Yellow screen for OPL 0.6), as you can run some games and see some graphics.
Unmodified SCPH-77006 with SM 3.6
SCPH-39006 with M-chip modchip, SCPH-10281 NA and refurb Seagate 80GB HDD
SCPH-10000 v1.00 with SCPH-10190 PCMCIA NA and SCPH-20400 HDD unit