[CentOS] How do I blank or overwrite DVD-RW disks in CentOS 5?

I'm trying to use DVD-RW ("minus RW") disks in my LG GSA-4040B
drive.  I can write a new disk just fine, but can't find any way to
blank or re-use a disk.  When I run xcdroast and click on the "Blank
CD/DVD+-RW" button, I get "Error while blanking."  Here is last part
of the dialog:

     Using generic SCSI-3/mmc DVD-R(W) driver (mmc_mdvd)
     Driver flags   : SWABAUDIO BURNFREE
     Supported modes: PACKET SAO
     Drive buf size : 1245184 = 1216 KB
     Drive DMA Speed: 11772 kB/s 66x CD 8x DVD
     cdrecord.prodvd: Success. set streaming: scsi sendcmd: no error
     CDB:  B6 00 00 00 00 00 00 00 00 00 1C 00
     status: 0x2 (CHECK CONDITION)
     Sense Bytes: F0 00 05 00 00 00 00 10 B6 00 00 0D 21 00 00 00
     Sense Key: 0x5 Illegal Request, Segmant 0
     Sense Code: 0x21 Qual 0x00 (logical block address out of range) Fru 0x0
     Sense flags: Blk 0 (valid)
     cmd finished after 0.004 s timeout 40s
     Current Secsize: 2048
     cdrecord.prodvd: Cannot set speed/dummy.
     ATIP start of lead in:  -150 (00:00/00)

I've had similar lack of success trying to blank or overwrite using
cdrecord or growisofs.  The disks I'm using are Sony 2X DVD-RW 4.7GB,
which _should_ be compatible with the drive AFAICT.  The drive is
happy to write to a new disk.

I'm not using KDE, so I'd prefer a command-line or Gnome tool.

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.