CD burning no longer working

[David Fleck]

System: FreeBSD 4.9-RELEASE-p11

dmesg:
acd0: <MSI CD-RW MS-8348/V140D> CD-RW drive at ata1 as master
acd0: read 689KB/s (6032KB/s) write 344KB/s (8273KB/s), 2048KB buffer, PIO4
acd0: Reads: CD-R, CD-RW, CD-DA stream, packet
acd0: Writes: CD-R, CD-RW, test write, burnproof
acd0: Audio: play, 255 volume levels
acd0: Mechanism: ejectable tray, unlocked
acd0: Medium: no/blank disc

The system has a CD-RW device which has, in the past, worked fine.  Trying 
to burn an .iso right now, however, and getting the following behavior:

  # burncd -f /dev/acd0c data /misc/backup_assemble/backup051105.iso fixate
  next writeable LBA 0
  writing from file /misc/backup_assemble/backup051105.iso size 408480 KB
  written this track 1472 KB (0%) total 1472 KB
  only wrote -1 of 32768 bytes err=5

  fixating CD, please wait..
  burncd: ioctl(CDRIOCFIXATE): Input/output error

while the kernel complains:
  Nov  5 09:15:10 grond /kernel: acd0: WRITE_BIG - MEDIUM ERROR asc=0x02 ascq=0x00 error=0x00
  Nov  5 09:15:10 grond /kernel: acd0: CLOSE_TRACK/SESSION - ILLEGAL REQUEST asc=0x72 ascq=0x04 error=0x00

Same behavior with 2 different CDs.
Used to work, now it doesn't, so I'm tempted to blame the hardware.  But 
does anyone have any more specific ideas of what might be going on here?

--
David Fleck
david.fleck at mchsi.com