I have Xubuntu 12.04 installed on my computer and there is an annoying problem with my mouse cursor. When I start the computer, it is usually fine, but if I leave it for a while it goes in sleeping mode, as it should, and then, e.g., in an hour I wake it up from sleeping mode, the mouse cursor is not there. Actually, it is only invisible but it is still active. If I hover with the mouse over some fields, they become highlighted as they should be when the mouse cursor is over them. Clicking on them also works fine. The only problem is that I don't see the cursor. If I restart the system, things move back to normal, but after the first sleeping mode the cursor disappears again. Does any one know a solution?