I found out that you must put your phone in Mass Storage mode, as default is MTP mode. As simple as that @#! And I spent hours trying all sorts of things reading posts.
Settings / Xperia / USB Connectivity / USB Connection Mode and select MASS Storage, not MTP. I did uncheck Install PC Companion. It work right away. No need to Update drivers, no need to change the android_winusb.inf. You may need to kill adb.exe before trying again adb devices.
That was it for me :)
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…