I have a really weird issue in connecting my Samsung GS2 to my Ubuntu 14.04 system.
I found the ID via lsusb at first, and added a udev entry. Everything was perfect and I was happily ADBing away for a few minutes. Thereafter, I begun getting "Unable to mount samsung device" (or something similar) popups.
Since then, my GS2 doesn't even show up in lsusb. When I plug it in, the phone behaves as if it has just been connected to a wall charger; MTP doesn't work any more, while it used to fine. I've tried removing the udev config file, restarting phone and pc, and enabling/disabling debugging mode, but still there's nothing in lsusb. Everything works perfectly on my other windows machine.
What on earth is going on here?