[ubuntu] Usability bugs

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http://ubuntuforums.org – Hello, I have installed Ubuntu 12.04(32 bits) in my laptop(64 bits). When I'm using the system the mouse click and keyboard commands like alt+tab stop to work. This problem happens frequently. I can still open Dash home and if I block screen and restart session it solves the problem but it comes back again after a while. Can someone help me about this issue pls? (Hardware)