Combo display error in IE

Hi,
As long as I load the combo box from local file system displaying is alright but loading via local webserver (tomcat) around the popup list is a large white box. In that I'm using about 100 items the popup isn't displayed at all just the white box.
To reproduce that just copy the combo.htm to your webserver and change bg-color to non-white, the same error occurs on friendsofaw website (demo3). The only difference I can see are different Security settings in IE "My Computers" works all others not.
I'm using IE 6.0.2900.2180.xpsp_sp2_gdr.050301-1519 (Bug doesn't appear in FF 1.5)
Does anybody know what setting causes this or how I can fix this?
Ta

I've found a solution for the examples/combo.htm adding the line below to the local style definition.

.aw-popup-window {margin:0px;}

Unfortunately that doesn't work in my app because of some more nested elements. Does anybody know the id of the displayed list or some more classes to overwrite the wrong setting?