Addition: I installed the Lubuntu desktop (wow... it's awesome), and this issue still exists, so it's not contained to Xubuntu. It also happens with LxTerm. If I move the panel from the top to the left, it blacks out just the same. I'm also using Nvidia driver (270.x.x) and using (a custom build) of 2.6.38.6 (stock kernel, not with Ubuntu mods).
Addition: I installed the Lubuntu desktop (wow... it's awesome), and this issue still exists, so it's not contained to Xubuntu. It also happens with LxTerm. If I move the panel from the top to the left, it blacks out just the same. I'm also using Nvidia driver (270.x.x) and using (a custom build) of 2.6.38.6 (stock kernel, not with Ubuntu mods).