try giving the menu button a z-index of maybe 1000 or something.
Code:
#menu {z-index:1000;}
giving it a z-index of 1 or 2 might do it, but at least giving it a bigger number ensures it's ALWAYS on top.
but that reminds me that with ie6, you get wierd bugs like if the element haslayout and stuff. such a headache. and a wierd thing where giving the parent a smaller z-index seems to solve it. >.<
hopefully it doens't get that complicated for you. play around with giving the element and maybe some parent elements z-index and hope it gets fixed with the first few.
