Issues with black boxes lingering with my dropdowns in Chrome

Hi I have a few sites that use a similar framework and they all have the same issue, when you hover over a menu that has a main level drop down and then sub-level dropdowns off of that initial drop down menu when you move off the menu the main sub-menu leaves behind a black box. Any ideas on how I can correct this? I have tested it in IE, Safari and Firefox with no issues, this is just a Chrome thing as far as I can tell. Check it out and let me know what you think.