FYI, I'm seeing this same problem on my system. I turned on hald debugging and captured this output.

Jan 12 16:30:03 orca hald[481]: 16:30:03.851 [I] device.c:1894: Removing locks from ':1.132'
Jan 12 16:30:19 orca hald[481]: 16:30:19.051 [I] osspec.c:251: SEQNUM=1516, ACTION=change, SUBSYSTEM=scsi, DEVPATH=/sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0, DEVNAME=, IFINDEX=0
Jan 12 16:30:19 orca hald[481]: 16:30:19.051 [I] hotplug.c:435: checking event /sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0
Jan 12 16:30:19 orca hald[481]: 16:30:19.051 [I] hotplug.c:121: /sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0 is a device (store)
Jan 12 16:30:19 orca hald[481]: 16:30:19.051 [I] device.c:5035: refresh_dev: subsys=scsi
Jan 12 16:30:19 orca hald[481]: 16:30:19.051 [D] hotplug.c:453: events queued = 0, events in progress = 0
Jan 12 16:30:19 orca hald[481]: 16:30:19.051 [D] hotplug.c:458: Hotplug-queue empty now ... no hotplug events in progress
Jan 12 16:30:19 orca orage: polling /dev/sr0 (every 2 sec): [549]: 16:30:19.053 [D] addon-storage.c:541: Media insertion detected on /dev/sr0
Jan 12 16:30:19 orca hald[481]: 16:30:19.054 [D] hald_dbus.c:1652: udi=/org/freedesktop/Hal/devices/storage_model_CD_Writer__9500, key=storage.removable.media_available
Jan 12 16:30:19 orca hald[481]: 16:30:19.054 [I] hald_dbus.c:3096: entering, local_interface=1
Jan 12 16:30:19 orca hald[481]: 16:30:19.055 [D] hald_dbus.c:3105: udi=/org/freedesktop/Hal/devices/storage_model_CD_Writer__9500
Jan 12 16:30:19 orca hald[481]: 16:30:19.055 [I] blockdev.c:1779: blockdev_rescan_device: udi=/org/freedesktop/Hal/devices/storage_model_CD_Writer__9500
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.061 [D] probe-storage.c:141: Doing probe-storage for /dev/sr0 (bus pci) (drive_type cdrom) (udi=/org/freedesktop/Hal/devices/storage_model_CD_Writer__9500) (--only-check-for-fs==1)
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.061 [D] probe-storage.c:192: Doing open ("/dev/sr0", O_RDONLY | O_NONBLOCK)
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.062 [D] probe-storage.c:198: Returned from open(2)
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.075 [D] probe-storage.c:342: Checking for optical disc on /dev/sr0
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.075 [D] probe-storage.c:350: Doing open ("/dev/sr0", O_RDONLY | O_NONBLOCK | O_EXCL)
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.078 [D] probe-storage.c:380: PROBE HAS EXCLUSIVE LOCK ON CDROM
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.080 [D] probe-storage.c:422: media size = 483153920
Jan 12 16:30:19 orca hald-probe-storage: [1570]: 16:30:19.080 [D] probe-storage.c:430: PROBE CLOSED LOCK ON CDROM
Jan 12 16:30:19 orca hald[481]: 16:30:19.081 [I] hald_dbus.c:1342: storage.cdrom.read_speed -> 5645
Jan 12 16:30:19 orca hald[481]: 16:30:19.081 [I] hald_dbus.c:1342: storage.cdrom.write_speed -> 2117
Jan 12 16:30:19 orca hald[481]: 16:30:19.081 [I] hald_dbus.c:1366: storage.removable.media_available -> True
Jan 12 16:30:19 orca hald[481]: 16:30:19.081 [I] hald_dbus.c:1350: storage.removable.media_size -> 483153920
Jan 12 16:30:19 orca hald[481]: 16:30:19.082 [I] blockdev.c:1735: hald-probe-storage --only-check-for-media returned 2 (exit_type=0)
Jan 12 16:30:19 orca hald[481]: 16:30:19.082 [I] blockdev.c:1751: Media insertion detected with file system on main block device; synthesizing hotplug add
Jan 12 16:30:19 orca hald[481]: 16:30:19.082 [I] hotplug.c:435: checking event /sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0/fakevolume
Jan 12 16:30:19 orca hald[481]: 16:30:19.082 [I] osspec.c:1016: hal_util_find_known_parent: '/sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0/fakevolume'->'/sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0'
Jan 12 16:30:19 orca hald[481]: 16:30:19.082 [I] blockdev.c:903: block_add: sysfs_path=/sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0/fakevolume dev=/dev/sr0 is_part=0, parent=0x0993ba90
Jan 12 16:30:19 orca hald[481]: 16:30:19.082 [I] blockdev.c:911: Handling /dev/sr0 as fakevolume - sysfs_path_real=(null)
Jan 12 16:30:19 orca hald[481]: 16:30:19.083 [D] hotplug.c:453: events queued = 0, events in progress = 1
Jan 12 16:30:19 orca hald-probe-volume: [1572]: 16:30:19.087 [D] probe-volume.c:365: Doing probe-volume for /dev/sr0#012
Jan 12 16:30:19 orca hald-probe-volume: [1572]: 16:30:19.123 [D] probe-volume.c:376: volume.block_size = 2048
Jan 12 16:30:19 orca hald-probe-volume: [1572]: 16:30:19.124 [D] probe-volume.c:380: volume.size = 483153920
Jan 12 16:30:19 orca hald-probe-volume: [1572]: 16:30:19.171 [D] probe-volume.c:411: Disc in /dev/sr0 has audio
Jan 12 16:30:19 orca kernel: [359343.666398] sr 1:0:0:0: [sr0] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jan 12 16:30:19 orca kernel: [359343.666407] sr 1:0:0:0: [sr0] Sense Key : Illegal Request [current] 
Jan 12 16:30:19 orca kernel: [359343.666416] sr 1:0:0:0: [sr0] Add. Sense: Illegal mode for this track
Jan 12 16:30:19 orca kernel: [359343.666426] end_request: I/O error, dev sr0, sector 0
Jan 12 16:30:19 orca kernel: [359343.666433] __ratelimit: 68 callbacks suppressed
Jan 12 16:30:19 orca kernel: [359343.666438] Buffer I/O error on device sr0, logical block 0
Jan 12 16:30:19 orca kernel: [359343.666445] Buffer I/O error on device sr0, logical block 1
Jan 12 16:30:19 orca kernel: [359343.666453] Buffer I/O error on device sr0, logical block 2
Jan 12 16:30:19 orca kernel: [359343.666459] Buffer I/O error on device sr0, logical block 3
Jan 12 16:30:19 orca kernel: [359343.666464] Buffer I/O error on device sr0, logical block 4
Jan 12 16:30:19 orca kernel: [359343.666469] Buffer I/O error on device sr0, logical block 5
Jan 12 16:30:19 orca kernel: [359343.666475] Buffer I/O error on device sr0, logical block 6
Jan 12 16:30:19 orca kernel: [359343.666480] Buffer I/O error on device sr0, logical block 7
Jan 12 16:30:19 orca kernel: [359343.666485] Buffer I/O error on device sr0, logical block 8
Jan 12 16:30:19 orca kernel: [359343.666490] Buffer I/O error on device sr0, logical block 9
Jan 12 16:30:19 orca kernel: [359343.676318] sr 1:0:0:0: [sr0] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jan 12 16:30:19 orca hald-probe-volume: [1572]: 16:30:19.226 [D] probe-volume.c:457: get_disc_type returned 0x08
Jan 12 16:30:19 orca kernel: [359343.676325] sr 1:0:0:0: [sr0] Sense Key : Illegal Request [current] 
Jan 12 16:30:19 orca kernel: [359343.676333] sr 1:0:0:0: [sr0] Add. Sense: Illegal mode for this track
Jan 12 16:30:19 orca kernel: [359343.676343] end_request: I/O error, dev sr0, sector 0
Jan 12 16:30:19 orca hald-probe-volume: [1572]: 16:30:19.227 [D] probe-volume.c:534: volume.disc.capacity = 483153920
Jan 12 16:30:19 orca hald-probe-volume: [1572]: 16:30:19.234 [D] probe-volume.c:568: volume_session_count = 13
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1342: volume.block_size -> 2048
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1350: volume.size -> 483153920
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1334: volume.disc.type -> unknown
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1366: volume.disc.has_audio -> False
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1366: volume.disc.has_data -> False
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1366: volume.disc.is_blank -> False
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1366: volume.disc.is_appendable -> False
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1366: volume.disc.is_rewritable -> False
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1366: volume.disc.has_audio -> True
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1334: volume.disc.type -> cd_rom
Jan 12 16:30:19 orca hald[481]: 16:30:19.238 [I] hald_dbus.c:1350: volume.disc.capacity -> 483153920
Jan 12 16:30:19 orca hald[481]: 16:30:19.273 [I] blockdev.c:414: entering; exit_type=0, return_code=0
Jan 12 16:30:19 orca hald[481]: 16:30:19.274 [I] blockdev.c:169: Add callouts completed udi=/org/freedesktop/Hal/devices/volume_part_1_size_483153920
Jan 12 16:30:19 orca hald[481]: 16:30:19.274 [D] device_store.c:516: adding 0x99589a0 to (linux.sysfs_path,/sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0/fakevolume)
Jan 12 16:30:19 orca hald[481]: 16:30:19.274 [I] hald.c:108: Added device to GDL; udi=/org/freedesktop/Hal/devices/volume_part_1_size_483153920
Jan 12 16:30:19 orca hald[481]: 16:30:19.274 [D] hotplug.c:453: events queued = 0, events in progress = 0
Jan 12 16:30:19 orca hald[481]: 16:30:19.274 [D] hotplug.c:458: Hotplug-queue empty now ... no hotplug events in progress
Jan 12 16:30:19 orca kernel: [359343.736206] sr 1:0:0:0: [sr0] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jan 12 16:30:19 orca kernel: [359343.736219] sr 1:0:0:0: [sr0] Sense Key : Illegal Request [current] 
Jan 12 16:30:19 orca kernel: [359343.736231] sr 1:0:0:0: [sr0] Add. Sense: Illegal mode for this track
Jan 12 16:30:19 orca kernel: [359343.736243] end_request: I/O error, dev sr0, sector 0
Jan 12 16:30:19 orca kernel: [359343.745937] sr 1:0:0:0: [sr0] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jan 12 16:30:19 orca kernel: [359343.745949] sr 1:0:0:0: [sr0] Sense Key : Illegal Request [current] 
Jan 12 16:30:19 orca kernel: [359343.745960] sr 1:0:0:0: [sr0] Add. Sense: Illegal mode for this track
Jan 12 16:30:19 orca kernel: [359343.745973] end_request: I/O error, dev sr0, sector 0
Jan 12 16:30:19 orca hald[481]: 16:30:19.298 [I] osspec.c:251: SEQNUM=1517, ACTION=change, SUBSYSTEM=block, DEVPATH=/sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0, DEVNAME=/dev/sr0, IFINDEX=0
Jan 12 16:30:19 orca hald[481]: 16:30:19.298 [I] hotplug.c:435: checking event /sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0
Jan 12 16:30:19 orca hald[481]: 16:30:19.298 [I] blockdev.c:1715: block_change: sysfs_path=/sys/devices/pci0000:00/0000:00:1f.1/host1/target1:0:0/1:0:0:0/block/sr0
Jan 12 16:30:19 orca hald[481]: 16:30:19.298 [D] hotplug.c:453: events queued = 0, events in progress = 0
Jan 12 16:30:19 orca hald[481]: 16:30:19.298 [D] hotplug.c:458: Hotplug-queue empty now ... no hotplug events in progress
Jan 12 16:30:21 orca orage: polling /dev/sr0 (every 2 sec): [549]: 16:30:21.002 [I] addon-storage.c:354: Checking whether device /dev/sr0 is locked on HAL
Jan 12 16:30:21 orca orage: polling /dev/sr0 (every 2 sec): [549]: 16:30:21.003 [I] addon-storage.c:362: ... device /dev/sr0 is not locked on HAL
Jan 12 16:30:52 orca hald[481]: 16:30:52.731 [I] device.c:1894: Removing locks from ':1.133'