I have reduced the problem to the smallest code required to reproduce it. It consists of a menu using an unsorted list <ul> in my MasterPage.master file with some css in the stylesheet.css (there are images referenced in the code, but not required to see the problem).
Here is what happens. When the project is run .. everything is fine, but in design mode (VS 2008) the menu is left-aligned in the masterpage (like is should be) but the menu appears right-aligned in any content page that uses that master page! There is NO other code in the content pages ... try it out, and if you can help I'd really appreciate it, I might even get some sleep tonight!
StyleSheet.css
#header{BACKGROUND:url(images/menu/bg.gif) #dae0d2 repeat-x 50% bottom;FLOAT:left;FONT-SIZE:93%;LINE-HEIGHT:normal;WIDTH:100%}
#header #current{background:url(images/menu/left_on.gif)}
#header #current A{background:url(images/menu/right_on.gif);COLOR:rgb(51,51,0);PADDING-BOTTOM:5px}
#header A{BACKGROUND:url(images/menu/right.gif) no-repeat right top;COLOR:rgb(102,85,0);DISPLAY:block;FLOAT:left;FONT-WEIGHT:bold;padding:5px 15px 4px 6px;TEXT-DECORATION:none}
#header A{FLOAT:none}
#header A:hover{COLOR:rgb(51,51,0)}
#header LI{BACKGROUND:url(images/menu/left.gif) no-repeat left top;FLOAT:left;font:small/1.1em Georgia,Serif;MARGIN:0px;padding:0px 0px 0px 9px}
#header UL{list-style:none;MARGIN:0px;padding:10px 10px 0px}
UNKNOWN{FONT-SIZE:small}
MasterPage.master code
<body>
<form id="form1" runat="server">
<center>
<asp:Panel ID="c2panel" runat="server">
<div id="header" >
<ul>
<li><a href= "../admin/default.aspx">Admin</a></li>
<li><a href="">Inventory</a></li>
<li><a href="">Manufacturing</a></li>
<li><a href="">Quality</a></li>
<li><a href="">Purchasing</a></li>
</ul>
</div>
<asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server">
</asp:ContentPlaceHolder>
</asp:Panel>
</center>
</form>
</body>
Thanks all!