public bool IsProjectOnExternalDisk(string driveLetter)
    {
        bool retVal = false;
        driveLetter = driveLetter.TrimEnd('\\');

        // browse all USB WMI physical disks
        foreach (ManagementObject drive in new ManagementObjectSearcher("select DeviceID, MediaType,InterfaceType from Win32_DiskDrive").Get())
        {
            // associate physical disks with partitions
            ManagementObjectCollection partitionCollection = new ManagementObjectSearcher(String.Format("associators of {{Win32_DiskDrive.DeviceID='{0}'}} " + "where AssocClass = Win32_DiskDriveToDiskPartition", drive["DeviceID"])).Get();

            foreach (ManagementObject partition in partitionCollection)
            {
                if (partition != null)
                {
                    // associate partitions with logical disks (drive letter volumes)
                    ManagementObjectCollection logicalCollection = new ManagementObjectSearcher(String.Format("associators of {{Win32_DiskPartition.DeviceID='{0}'}} " + "where AssocClass= Win32_LogicalDiskToPartition", partition["DeviceID"])).Get();

                    foreach (ManagementObject logical in logicalCollection)
                    {
                        if (logical != null)
                        {
                            // finally find the logical disk entry
                            ManagementObjectCollection.ManagementObjectEnumerator volumeEnumerator = new ManagementObjectSearcher(String.Format("select DeviceID from Win32_LogicalDisk " + "where Name='{0}'", logical["Name"])).Get().GetEnumerator();

                            volumeEnumerator.MoveNext();

                            ManagementObject volume = (ManagementObject)volumeEnumerator.Current;

                            if (driveLetter.ToLowerInvariant().Equals(volume["DeviceID"].ToString().ToLowerInvariant()) &&
                                (drive["MediaType"].ToString().ToLowerInvariant().Contains("external") || drive["InterfaceType"].ToString().ToLowerInvariant().Contains("usb")))
                            {
                                retVal = true;
                                break;
                            }
                        }
                    }
                }
            }
        }

        return retVal;
    }