I don't really know what to call this problem, but it happens to me a lot.
Sometimes when ever I right click anywhere that a right click dialog would popup, the dialog pops up like normal, but as soon as I make a selection, what ever I selected stays on the screen, but the rest of the menu goes away. Then that stupid menu stays on top of every window, kind of like a window that is set to always on top.
In the attached screenshot, think of the grey area as my current active window. Now try clicking on something bellow the "Open File(s)..." box that is there. You can't.
I was wondering if anyone knew why this happens. Pretty much the only way to get rid of it is to restart my computer. I also would like to point out that I do have the newest drivers for my graphics card, and I have had this problem on both this current graphics card and windows installation, and on my old computer which had a different card and windows installation, so I wouldn't think it would be a graphics card issue, but maybe a stupid windows bug or something.
Here is another example with the same bug.