Some of the most frequent answers to fix a problem are in reference to the menu not being placed correctly when using relative positioning i.e. putting the menu in a table or div correctly. It is not recommended that the menu be placed in a div, but many do, and these would apply in those circumstances, also.
This is just a quick 'screenshot' guide for how to do this, and is very short. It contains a zip file with two pages, one for each method used to place the menu in a table. The same methods would apply to a div. See the links below this example for a more indepth explanation as to the whys and wherefores, and the menu sample for relatively positioned table menus.
Table Placement Example Page
For more more indepth explanation and directions on how to place the menu in the table see
Embedding the Menu in a Table Cell and also the table based menu sample
Ruth