Since here every day again and again problems with the USB VCOM driver installation for MTK6577 appear Phones, here is a short guide to the installation, and a final, successful test with SPFlashtool! Installation of the USB VCOM driver:  With USBDeview, clean up your PC from all possible old MTK VCOM entries, then reboot your PC.Enlaces Patrocinados (regístrate y no los verás :) ):  Smartphone is switched off, and still dont connect via USB to the PC.  Open Device Manager and leave it open!  Your switched off Smartphone with inserted rechargeable battery via USB connect now on the PC, you should now see a MT65xx preloader in the Device Manager. (With some MTK6577 Smartphones should be installed without battery. Please before hand inform.)  now launch the Installdriver.exe from the unzipped MT6577 USB VCOM drivers folder. Confirm the installation of unsigned drivers  now! (W7 x 64 this confirmation comes later in the manual installation!) After the installation is complete, you have no entry in the Device Manager, it is correctly!  PC reboot!  Open Device Manager and open the switched-off Smartphone via USB to the PC release, now connect (same USB port!)  Now a MediaTek PreLoader USB VCOM should appear for a brief moment in the Device Manager entry!  At the moment the entry double click and click on "Update driver" under the tab "Driver".  With the wizard in the unzipped MTK 6577 USB VCOM drivers navigate and select the folder for your operating system. Quote: [TABLE] <tbody>[TR] [TD="class: alt2, bgcolor: #E9E9E9"]Required Downloads: Download MT6577 USB VCOM Driver (W7/Vista/XP) -> http://www.mediafire.com/?cypm22rgs2k83ji Download MT6577 USB VCOM Driver (W8) -> http://www.mediafire.com/?7yee2of64nhl947 Download USBDeview -> http://www.mediafire.com/?becpnj761zh5o2w Download USBDeview x64 -> http://www.mediafire.com/?41i2k36yyi1fzhz[/TD] [/TR] </tbody>[/TABLE] Saludos y suerte.