[ubuntu] Ubuntu stops recognize Android device

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http://ubuntuforums.org – I used to access my Android device through nautilus but sunddely my Ubuntu stops recognize the usb port. (Yes, I switched usb ports already!) I type lsusb on console but my androids doesn't appears anymore. There isn't any clue in dmesg or syslog. Someone can help me? Ubuntu: 12.04 Android device: Samsung Galaxy Tab 7" GT-P1000L (Froyo) (Hardware)