usb mass storage failure

[vdm.fbsd at virgilio.it]

Context: freebsd 5.4

Dear All,

My brand-new usb mp3 reader, even though is seen as a flash disk by the OS,
cannot be used because:

(/var/log/message extract)

umass0: vendor 0x10d6 USB 2.0(FS) FLASH DISK, rev 1.10/1.00, addr 2
da0 at umass-sim0 bus 0 target 0 lun 0
da0: <USB2.0 (FS) FLASH DISK 1.00> Removable Direct Access SCSI-0 device
da0: 1.000MB/s transfers
da0: 497MB (1019617 512 byte sectors: 64H 32S/T 497C)
umass0: BBB reset failed, STALLED
umass0: BBB bulk-in clear stall failed, STALLED
umass0: BBB bulk-out clear stall failed, STALLED
(da0:umass-sim0:0:0:0): Synchronize cache failed, status == 0x4, scsi status
== 0x0
umass0: BBB reset failed, STALLED
umass0: BBB bulk-in clear stall failed, STALLED
umass0: BBB bulk-out clear stall failed, STALLED
umass0: BBB reset failed, STALLED
...........................................
umass0: BBB bulk-in clear stall failed, STALLED
umass0: BBB bulk-out clear stall failed, STALLED
Opened disk da0 -> 5
umass0: BBB reset failed, STALLED
umass0: BBB bulk-in clear stall failed, STALLED
umass0: BBB bulk-out clear stall failed, STALLED
umass0: BBB reset failed, STALLED
.............................................................
Opened disk da0 -> 5
umass0: at uhub0 port 2 (addr 2) disconnected
(da0:umass-sim0:0:0:0): lost device
(da0:umass-sim0:0:0:0): removing device entry
umass0: detached
...............................

Anyone out there could tell me why it happens and what I should do?

Thanks
Vittorio