Maximize, minimize and close buttons are either not present or not working in Lubuntu

As the title indicates, the maximize, minimize, and close buttons are either not present or not working on my Lubuntu desktop. In fact, it only seems to be Google Chrome that displays the buttons at all, and only the close button works in Chrome, maximize and minimize don't do anything. When I use regular Ubuntu, they're all there just fine but not on Lubuntu. This all seemed to occur after I hooked my netbook up to an external monitor while using Lubuntu. Not sure if that had anything to do with it or not, but it seemed too big of a coincidence to not mention. Any ideas what the cause and a fix might be?

Thanks in advance.