u cud try the riter on diff media and on diff computer.ur riter is quite decent , so i expect it's ur source ( HDD mostly ) that is slow . try riting data from diff drive , defragment drives.
what s the capakity of ur HDD partition from wich u are riting ?
try riting an image first and burn the image.
if all these fail try changing the cables ( power cable , master slave combi , etc.. )
PS , do all these if the problem is repeating !!