This is a problem I have encountered as well, but I am not so sure that the above mentioned problem is actually my problem. I have two different websites hosted with two different companies: a bluehost site and a godaddy site. I have no problem with the wp left menu (dashboard, media, pages, etc.) at all on my godaddy hosted site, however on my bluehost site, this is a very frustrating issue, as all of the menu items overlap each other randomly and when mousing over them and attempting to click, I inadvertently click on an unintended target. I am on Win 8 on a laptop. I access both sites from the same computer.