New answers tagged usb-debugging
Try installing the Microsoft User-Mode Driver Framework (http://support.microsoft.com/kb/2685813). It will require a restart. Worked for me, Nexus 5, Windows 7 SP1. I tried the Google USB Driver (http://developer.android.com/sdk/win-usb.html) but it didn't fix the issue for me. The Microsoft User-Mode Driver Framework, however, did.
I'm sure this is not exactly the answer you're looking for, but this could solve your problem: If your Nexus works fine otherwise, why don't you just plug a mouse and keyboard (via USB OTG or Bluetooth) and pretend your Nexus does not have touch screen? Anything, including allowing USB debugging would work as the mouse cursor is even usable when your phone ...
I had my digitizer burned (by flashing corrupted recovery) and flashed new ROM and I was able to proceed as described here: http://android.stackexchange.com/a/69600/60711
From command prompt you can enter the following command adb kill-server and then try ejecting.
You can't do this with the old "Android browser", but you can in Chrome, which is downloadable from Google Play and comes installed on all recent Android devices. The feature you're looking for is called Chrome Remote Debugging, and it relies on having Chrome on your desktop and ADB enabled and connected.
The dialog you mention is nothing to do with USB debugging: it's because the device's storage is mounted (via MTP or USB mass storage), and some app has a file open from that storage. It could be that you have a file manager window looking at the device's storage, or that your music player software is automatically indexing files on it, or something else. ...
Top 50 recent answers are included