can you dmesg after you plug in and mount your usb drive?
It might because the usb drive is write protected (not by OS)
FAT: Directory bread(block 15756) failed
FAT: Directory bread(block 15757) failed
FAT: Directory bread(block 15758) failed
FAT: Directory bread(block 15759) failed
FAT: Filesystem error (dev sdc1)
fat_get_cluster: invalid cluster chain (i_pos 0)
FAT: Filesystem error (dev sdc1)
fat_get_cluster: invalid cluster chain (i_pos 0)
EFS: 1.0a -
http://aeschi.ch.eu.org/efs/FAT: utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive!
FAT: Filesystem error (dev sdc1)
fat_get_cluster: invalid cluster chain (i_pos 0)
FAT: Filesystem has been set read-only
FAT: Filesystem error (dev sdc1)
fat_get_cluster: invalid cluster chain (i_pos 0)
FAT: Filesystem error (dev sdc1)
fat_get_cluster: invalid cluster chain (i_pos 0)
FAT: Filesystem error (dev sdc1)
fat_get_cluster: invalid cluster chain (i_pos 0)
i dont think that my usb drive lock itself..