your drive might be faulty.
if possible, try to take it out and put it into another computer, see if it works there (might be some kind of system mess-up, software incompatibility, ASPI probelm...)
try using higher quality media. Taiyo Yuden if you know how to get some. perhpas Verbatim DataLifePlus
(though i don't know if your drive likes these discs).
try updating the firmware of your drive. look at the manufacturer's website to see if there's a newer firmware for your drive.
too see what firmware you drive has now you can use a utility such as Nero InfoTool ( http://www.cdspeed2000.com/files/NeroInfoTool_227.zip
). i'm sure RecordNow also shows this info in Drive Properties (or something like that).
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