I have installed Ubuntu 12.04 LTS on my notebook and use a USB keyboard connected to it. Everything worked ok, but since this morning, when configuring the WiFi network of my work, accelerators which included CTRL ALT stopped working. For example, CTRL ALT T for a new terminal does not work, but it does if you use the keyboard of the notebook at the same time. (And so on, move from workspace, move a window to another workspace, lock the desktop, etc). I tried rebooting without the keyboard connected but nothing.