Across multiple applications, when I click wit my pointing device to summon a menu, a selection is often made from options on the menu before the menu has even been up long enough to be read.  In fact, I am not sure that the menus always make an appearance!  The selection seems random, though I would guess that it has something to do with the order or position of the option selected.  This behavior occurs both with menus summoned by right-clicks and with those summoned by left-clicks.

An example would be in clicking on "File" in gedit, with the intention of opening a file, but having the Quit selection implicitly chosen! (Potentially dire when multiple files are being edited.) I most often have this problem with Firefox, when right-clicking on a linked element, but that it largely an artefact of using Firefox heavily.

I'm using Xfce 4.8.  I'm running Fedora Linux Core 17, on a Dell Inspiron Mini 1012 (Intel Atom N450), while using a Logitech M510 mouse. and have had the problem with various kernels (presently with 3.5.3).

I don't experience this problem when, with this same hardware, I run Gnome on Scientific Linux, or (G_d help me!) Windows 7.