DRU-510UL Data corruption

[Jinnah Dylan Hosein <jdh@jdh.org>]

I'm using a Sony DRU-510UL Firewire/USB 2.0 DVD±RW drive.
I am consistently getting data corruption when burning dvd's

I've tried DVD+RW and DVD-RW media. I've used cdrecord-prodvd and 
dvd+rw-tools. I've tried burning using the ieee1384 and usb 2.0 interfaces

both cdrecord-prodvd and dvd+rw-tools burn the disks without complaint. I
can format, blank and burn with no errors reported. After burning I do
md5sums of the files on the dvd and the source files on the file system.  
For some large files (generally over 30mb) the md5sums will be different.  
large tgz files are corrupted and cannot be fully untared.

I'm using redhat-8.0 with the  2.4.20-19.8 kernel from redhat.

it rather frustrating. nothing is reporting errors but the dvd's always 
end up with errors on them.

I don't know what to try next. any suggestions?
thanks,
-jdh