[arch-general] usb disk not visible

I have a problem with an external USB disk here, which is a WD 500Gb bought last year. Recently I decided finally to format it to ext3, since I'm using Linux everywhere, but now I don't seem to see it from my dell latitude. On my mini dell everything works perfectly, but on the latitude I get only this from dmesg [ 8916.825474] usb 2-1.2: USB disconnect, device number 11 [ 8917.013895] usb 2-1.2: new high-speed USB device number 12 using ehci_hcd [ 8919.126604] usb 2-1.2: USB disconnect, device number 12 [ 8919.314274] usb 2-1.2: new high-speed USB device number 13 using ehci_hcd and fdisk doesn't detect anything: [andrea@dell]$ sudo fdisk -l /dev/sdb Any idea of what it could be?