The operating system is informing you that there are still files open by your operating system. This can be either because there are still files that are meant to be written but are still cached, or that the operating system is using the drive for background processes such as indexing or temporary space. To identify the process that is accessing your disk, you may use a third party tool such as Microsoft Process Explorer (http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx.) Please refer to the tools documentation as to instructions in its use.
To minimize the possibility of OS controlled open files, make sure to set the disk optimization for quick removal. To change Windows' caching algorithm, open the disk management console located at WindowsSystem32diskmgmt.msc on your system drive- For Vista and Windows 7, make sure to run this applet as administrator! A list of the attached drives and their respective volumes will appear. Right-click on the Fantom external disk in the disk list and select properties. Select the Policies Tab near the top left of the window, and click your desired optimization level. press OK when finished, and you may close the disk management applet.
