Firefox seems to read this fine, however, IE is being anal.
<div style="width:760px; height:120px;">
<div style="width:300px; height:60px; margin:0px auto;">
</div>
</div>
this proportions the inner layer to 0px top auto left/right
ProfK: <div style="height:600px; vertical-align:middle; text-align:center;">
<asp:Label runat="server" ID="displayLabel"></asp:Label>
</div>
in your exampl the div layer has the same width as the inner <input> tag and will not "center" itself to the holding container. middle align won't happen because vertical-align does not know what your upper/lower boundries are. try setting the <input> to be absolutely positioned within the holding container, that would give it a free float?
'Not everything is binary, if you look closer you might find some hexadecimal in there somewhere'