I bought a used Droid 3 and i have two microusb cables both are LG. The cable works fine when it used for fastboot, but when i turn on the phone and try to plug it nothing happens. It wont even show the menu that allows you to select what mode you want the phone to be in. I have enabled/disabled and re-enabled USB debugging to no avail.
I have tried everything, it is so strange it simply wont recognize the device neither in windows or os x, but it works in fastboot mode.