My problem is very simple apparently but a tricky one.
I just installed the Ubuntu 12.04(1) along with the Gnome3-shell environment on my new PC desktop Acer Aspire X3995 (see config below). Everything work (more or less) so far (I still have problems of sound and disabled 2-fingers gestures with my screen -- which I will have to deal with xconfig settings I think -- though), but the main problem is that I cannot select files/folders with my USB mouse.
When I try to double click on them, nothing happen (sometimes one folder or file is selected but then unselected again). Note that the navigation works perfectly from the USB keyboard and from the touch-screen. (I am using a 23" wide touch-screen Acer Monitor T231Hbmid).
Also, the mouse works perfectly with other menu navigation, with the only difference that the text of certain menus is selected as if I was holding the left click on them. So I assume the problem is only related to the mouse.
Needless to say that the usual basic hardware checks have been performed (unplugging, powered-off, etc.).
My level is simply "advanced user", meaning that if you provide me with intelligible input I should find my way, but please don't expect too much technical/specific knowledge.
Please let me know if you need more information on this bug.
Config of Acer Aspire X3995: Ubuntu 12.04 / Gnome3-shell environment / Intel Core i5 3450 / nVidia GeForce 605, 1Gb.
Screen: Acer Monitor TFT 23" wide T231Hbmid