I used to be able to see and manage my iPod with different softwares: Amarok, Rhythmbox, GTKPod. The device is a nano 1st generation 4gb.

Currently it mounts regularly and can be accessed from the file system, but I get this in dmesg:

[ 1547.617891] scsi 11:0:0:0: Direct-Access     Apple    iPod             1.62 PQ: 0 ANSI: 0
[ 1547.619103] sd 11:0:0:0: Attached scsi generic sg2 type 0
[ 1547.620478] sd 11:0:0:0: [sdb] Adjusting the sector count from its reported value: 7999488
[ 1547.620494] sd 11:0:0:0: [sdb] 7999487 512-byte hardware sectors: (4.09 GB/3.81 GiB)
[ 1547.621718] sd 11:0:0:0: [sdb] Write Protect is off
[ 1547.621726] sd 11:0:0:0: [sdb] Mode Sense: 68 00 00 08
[ 1547.621732] sd 11:0:0:0: [sdb] Assuming drive cache: write through
[ 1547.623591] sd 11:0:0:0: [sdb] Adjusting the sector count from its reported value: 7999488
[ 1547.624993] sd 11:0:0:0: [sdb] Assuming drive cache: write through
[ 1547.625003]  sdb: sdb1 sdb2
[ 1547.629686] sd 11:0:0:0: [sdb] Attached SCSI removable disk
[ 1548.084026] FAT: utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive!
[ 1548.369502] FAT: utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive!
[ 1548.504358] FAT: invalid media value (0x2f)
[ 1548.504363] VFS: Can't find a valid FAT filesystem on dev sdb1.
[ 1548.945173] FAT: utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive!
[ 1548.945179] FAT: invalid media value (0x2f)
[ 1548.945182] VFS: Can't find a valid FAT filesystem on dev sdb1.
[ 1610.092886] usb 2-6: USB disconnect, address 9

The only application that can access it (partially) is Rhythmbox. I say partially because I can transfer files to the iPod but can't remove or modify them. Also one transfer didn't finish and only 9 out of 16 songs were delivered to the device. All other softwares I tried (GTKPod, Amarok, Songbird) don't even detect it.

What can I do to troubleshoot this?

EDIT:

# fdisk -l /dev/sdb

Disk /dev/sdb: 4095 MB, 4095737344 bytes
241 heads, 62 sectors/track, 535 cylinders
Units = cylinders of 14942 * 512 = 7650304 bytes
Disk identifier: 0x20202020

Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1          11       80293+   0  Empty
Partition 1 has different physical/logical beginnings (non-Linux?):
    phys=(0, 1, 1) logical=(0, 1, 2)
Partition 1 has different physical/logical endings:
    phys=(9, 254, 63) logical=(10, 181, 8)
Partition 1 does not end on cylinder boundary.
/dev/sdb2              11         536     3919415+   b  W95 FAT32
Partition 2 has different physical/logical beginnings (non-Linux?):
    phys=(10, 0, 7) logical=(10, 181, 15)
Partition 2 has different physical/logical endings:
    phys=(497, 240, 62) logical=(535, 88, 61)

EDIT2:

The "before" state is hard to tell, it was a lot of updates ago. Haven't been using my iPod for a while so I can't say when exactly it stopped working. I'm sure Amarok was still at version 1.X but can't remember when it was. My current system is debian testing fully updated.

NOTE: just noticed that if I mount the device manually instead of letting nautilus automount it, I can see it again on GTKPod but still not on Banshee AND it's vanished from Rhythmbox...