Drop Down menu rollover issues

Using Google Chrome Browser.... On my site HMQS Gayundah when using the main (black) drop down menu, there is a small gap between the top menu item and the drop down items. As I roll over that gap the drop down items disappear. (As obviously it thinks I'm positioned over the slider as opposed to the menu. Now I've checked with Waterfox and IE and it is not experiencing the same issue. The problem seems to be confined to Google Chrome. This problem is new it has always worked fine with Chrome previously.