Small but growing. Welcome to CD Freaks.

I would expect the drive to have a proper write strategy for
Verbatim 16x media so it looks like something is wrong.

Try running "dmesg | grep DMA"
You should have DMA enabled for your DVD writer and your
hard-drive.

If hdparm is installed on your system, you can use it to
check and change your DMA settings.

Is your hard-drive working properly? Have you got the right
kernel drivers for your drive controller? Is it IDE, SATA or
SCSI? You can do a hard-drive read speed test with hdparm
or dd.

hdparm -tT /dev/xxx where xxx is the drive device name. Usually
hda or sda for your hard-drive.

or

dd bs=512 count=1000000 if=/dev/xxx of=/dev/null

Both of these commands need root privileges so be careful
how you use them.