I have the same problem but it is not a corrupt file structure.
1) I have a secure enabled external hard drive that is recognized by my old laptop and my desk top at home. I tried to install Secure Lock Ware on a new laptop with the external drive turned on and plugged into the laptop, installer said that it found a device and needs to reboot. However, after the reboot, it still would not recognize the drive and gave me the same "Target device was not found". The same drive is still being recognized by my desk top.
2) I also have a Secure Lock Ware enabled internal hard drive on a work desk top. When the work desk top was upgraded with a new computer, the drive was seen on Disk Manager but as an unpartitioned drive. I down loaded the Secure Lock Ware (SLW) program and installed it on the desk top. At the end of the installation, the computer again recognized the device and asked to reboot. After the reboot, Secure Lock Ware automatically recognized the drive and prompted for the password. Drive was accessed with no problem.
All being said, do not format your drive. Buffalo needs to have a patch for this problem for the external hard drive.