USB pendrive not mounted, errors in DMESG

[Call Me Ishmael]

Hi, I installed Ubuntu, and it's just great :-)

Unfortunately I have a problem with my usb mp3 player, Medion PRO2 256 MB. 
This player acts like as a normal usb pendrive, and it works smoothly with a Knoppix 
and a Debian Woody (both kernels 2.4-xx) on the same PC on /dev/sda1, so there is no 
hardware incompatibility.
When I plug it on the usb port with Ubuntu warty, the device doesn't get automounted, 
and this wouldn't be a problem, because I know how to do it by hand. The problem is 
that i can't do it because I don't have any /dev/sdaXX device! I also tried to create 
/dev/sda1 by hand, and I tried mknod b 8 0, but when I try to mount the key I got a "not 
a valid block device" error.
Sometimes the mp3 player hangs when plugged, and I have to remove the battery to 
reset it.

>From the dmesg output, hereby attached, it seems that the pendrive is recognized 
correctly (name and size information are correct) but then is disconnected from the hub. 
(hub 1-0:1.0: port 2 disabled by hub (EMI?), re-enabling...)

I've no clues, I searched on Google but I didn't find any solution.

Any help would be greatly appreciated! 

Thanks , Ishmael 


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The lshal output is:
*** [DIE] lshal.c:dump_devices():70 : Couldn't obtain list of devices

-------------------------------------------------
The dmesg output, taken after plug in, but before to plug out  is: 

usbcore: registered new driver usbfs
usbcore: registered new driver hub
ohci_hcd: 2004 Feb 02 USB 1.1 'Open' Host Controller (OHCI) Driver (PCI)
ohci_hcd: block sizes: ed 64 td 64
PCI: Found IRQ 10 for device 0000:00:02.0
ohci_hcd 0000:00:02.0: ALi Corporation USB 1.1 Controller
ohci_hcd 0000:00:02.0: irq 10, pci mem e090b000
ohci_hcd 0000:00:02.0: new USB bus registered, assigned bus number 1
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
PCI: Found IRQ 9 for device 0000:00:0e.0
NET: Registered protocol family 10
Disabled Privacy Extensions on device c02cc0c0(lo)
IPv6 over IPv4 tunneling driver
acpi: Unknown symbol acpi_processor_unregister_performance
acpi: Unknown symbol acpi_processor_register_performance
ohci_hcd 0000:00:02.0: wakeup
usb 1-2: new full speed USB device using address 2
SCSI subsystem initialized
Initializing USB Mass Storage driver...
scsi0 : SCSI emulation for USB Mass Storage devices
  Vendor: SigmaTel  Model: MSCN              Rev: 0100
  Type:   Direct-Access                      ANSI SCSI revision: 02
USB Mass Storage device found at 2
usbcore: registered new driver usb-storage
USB Mass Storage support registered.
SCSI device sda: 505600 512-byte hdwr sectors (259 MB)
sda: Write Protect is off
sda: Mode Sense: 03 00 00 00
sda: assuming drive cache: write through
 /dev/scsi/host0/bus0/target0/lun0:SCSI error : <0 0 0 0> return code = 0x70000
end_request: I/O error, dev sda, sector 0
Buffer I/O error on device sda, logical block 0
SCSI error : <0 0 0 0> return code = 0x70000
end_request: I/O error, dev sda, sector 0
Buffer I/O error on device sda, logical block 0
 unable to read partition table
Attached scsi removable disk sda at scsi0, channel 0, id 0, lun 0
hub 1-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
usb 1-2: USB disconnect, address 2
usb 1-2: new full speed USB device using address 3
scsi1 : SCSI emulation for USB Mass Storage devices