Parent Child Relationships With MouseOvers

I hope I am posting to the correct list...

Hi, 
	I'm writing a series of dropdown menus that make use of DIVS and
Javascript to hide and show the menus.  I am using standard HTML 4 code.  I
have noticed that if I have a link and have the display set to 'BLOCK' when
I mouseover a link and set to 'NONE' when I MouseOut of the DIV, if I have
any HTML element in the DIV (say I put an Unordered List in the DIV), the
minute I roll over the Unordered List, the DIV vanishes.  That sort of makes
sense, in that I am rolling over a new element, but the UL is a child of the
DIV, correct?
	If I put code in the UL to continue to show the DIV if I roll over
that, the DIV will continue to show, even if I rollover an LI element.  So,
within lists, the parent-child relationship is maintained between a UL and
an LI, but not between a DIV and a UL.
	Is this a feature of HTML written into the spec, or a bug of IE
created by Microsoft?

	TIA,
	Maurice Reeves