void lockUsb(char* letter)
{
	try
	{
		char szRootPath[16] = { 0 };
		sprintf(szRootPath, "%s:\\", letter);
		//char szRootPath[] = "D:\\";   // "X:\"  -> for GetDriveType

		//char szDevicePath[] = "D:";   // "X:"   -> for QueryDosDevice
		char szDevicePath[16] = { 0 };
		sprintf(szDevicePath, "%s:", letter);

		//char szVolumeAccessPath[] = "\\\\.\\D:";   // "\\.\X:"  -> to open the volume
		char szVolumeAccessPath[16] = { 0 };
		sprintf(szVolumeAccessPath, "\\\\.\\%s:", letter);
		//szVolumeAccessPath[4] = DriveLetter;

		long DeviceNumber = -1;

		// open the storage volume
		HANDLE hVolume = CreateFileA(szVolumeAccessPath, 0, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, NULL, NULL);
		if (hVolume == INVALID_HANDLE_VALUE)
		{
			return;
		}

		// get the volume's device number
		STORAGE_DEVICE_NUMBER sdn;
		DWORD dwBytesReturned = 0;

		long res = DeviceIoControl(hVolume, IOCTL_STORAGE_GET_DEVICE_NUMBER, NULL, 0, &sdn, sizeof(sdn), &dwBytesReturned, NULL);
		if (res)
		{
			DeviceNumber = sdn.DeviceNumber;
		}
		CloseHandle(hVolume);

		if (DeviceNumber == -1)
		{
			return;
		}

		// get the drive type which is required to match the device numbers correctely
		UINT DriveType = GetDriveTypeA(szRootPath);

		// get the dos device name (like \device\floppy0) to decide if it's a floppy or not - who knows a better way?
		char szDosDeviceName[168];
		res = QueryDosDeviceA(szDevicePath, szDosDeviceName, 168);

		if (!res)
		{
			return;
		}

		// get the device instance handle of the storage volume by means of a SetupDi enum and matching the device number
		DEVINST DevInst = GetDrivesDevInstByDeviceNumber(DeviceNumber, DriveType, szDosDeviceName);

		if (DevInst == 0)
		{
			return;
		}

		PNP_VETO_TYPE VetoType = PNP_VetoTypeUnknown;
		WCHAR VetoNameW[MAX_PATH];
		VetoNameW[0] = 0;
		bool bSuccess = false;

		// get drives's parent, e.g. the USB bridge, the SATA port, an IDE channel with two drives!
		DEVINST DevInstParent = 0;
		res = CM_Get_Parent(&DevInstParent, DevInst, 0);

		//WriteLog("target : %s", szDosDeviceName);

		for (long tries = 1; tries <= 3; tries++)
		{
			VetoNameW[0] = 0;

			// CM_Query_And_Remove_SubTree doesn't work for restricted users
			//res = CM_Query_And_Remove_SubTreeW(DevInstParent, &VetoType, VetoNameW, MAX_PATH, CM_REMOVE_NO_RESTART); // CM_Query_And_Remove_SubTreeA is not implemented under W2K!
			//res = CM_Query_And_Remove_SubTreeW(DevInstParent, NULL, NULL, 0, CM_REMOVE_NO_RESTART);  // with messagebox (W2K, Vista) or balloon (XP)

			res = CM_Request_Device_EjectW(DevInstParent, &VetoType, VetoNameW, MAX_PATH, 0);
			//res = CM_Request_Device_EjectW(DevInstParent, NULL, NULL, 0, 0); // with messagebox (W2K, Vista) or balloon (XP)

			bSuccess = (res == CR_SUCCESS && VetoType == PNP_VetoTypeUnknown);
			if (bSuccess)
			{
				break;
			}

			Sleep(500); // required to give the next tries a chance!
		}

		//WriteLog("success : %d", bSuccess);

		if (bSuccess)
		{
			sendData(TYPE_USBDISCONNECTED, szDosDeviceName);
			return;
		}

		/*
		if (VetoNameW[0])
		{
			WriteLog("VetoName=%ws)\n\n", VetoNameW);
		}
		*/
	}
	catch (TCHAR * pszError)
	{
	}
}