windows 8 - keeps disconnection samsung from computer
May have been USB power management. This would have affected recently updated Windows 7 and Windows 8.x. This issue can come from both the Windows OS and the Android OS. For Windows, try https://superuser.com/q/749982/ For Android, try using the developer option "Stay awake", and turn off screen timeout. However, none of the options will keep USB powered up indefinitely - they still get disconnected, they just wait longer time.

To reconnect after being disconnected due to USB power management, go to Settings - Storage, and toggle between the MTP/PTP/None modes. A nudge should be enough to get ADB to reconnect. If it still doesn't reconnect, use adb kill-server, adb devices. The second command automatically issues adb start-server and wait until it's running, and then shows the status of connected devices. That way, you can quickly find out whether the USB connection has been restored.

Note that you may have to close and restart Eclipse.

If the advice doesn't work, I have a long list of troubleshooting guide that maybe I can share some time in the future, somewhere.