you should read carefully all the instructions on this page:
the 1612_1004.zip file you downloaded from the firmware page http://forum.rpc1.org/dl_firmware.php?download_id=191
is a regular firmware, not the hacked firmware.
it's the firmware that is now in your drive!
according to http://hijacker.rpc1.org/toshiba_nolimit/
your drive can't read DVD+R/W with 1004 firmware. i'm not sure i understand correctly but maybe with 1806 firmware you can.
in any case if you use one of the hacked firmwares you can.
since your drive is a Toshiba SD-M1612 revision A, you should download
Patched J004 firmware (RPC-1, No Read Limit)
Patched J806 firmware (RPC-1, No Read Limit, 48x CD read)
(both listed under Toshiba SD-M1612 RevA
you can make a bootable floppy using this:
(thaken from >NIL:'s incomplete FAQ here: http://pioneerdvd.rpc1.org/Firmware_FAQ.html
it's a WinME bootdisk with lots of useful drivers (like reading NTFS!).
worked like a charm for me.
but for flashing a Toshiba drive you don't want to load any drivers, just hit shift-F5 at the menu to get to a command prompt.
One Ring to rule them all, One Ring to find them,
One Ring to bring them all and in the darkness bind them
In the land of Mordor, where the Shadows lie
M.C. Escher - Reptilien