My Lexar 16gb usb flash drive is showing very strange activities. Sometimes it is showing in the drive list and when I click the properties it shows- used space: 0 bytes, 0 bytes and Free space : 0 bytes 0 bytes. But in the general device status it shows-the device is working properly. When I go to volume it shows-Type:Unknown, Status:Unreadable, Partition style: Not Applicable, Capacity:0 MB, Unallocated space: 0MB, Reserved space: 0 MB. It is not showing in the disk management system. Once I proceed to format it but it tells me you have no sufficient authority to do this. I have updated the drivers, it says driver is up to date and changed the drive letter several times but no result. Sometimes the windows can not recognize it. I do not know what's the problem is. Do you have any suggestions?