Improving the solution suggested by gdoron and Jasen by changing the _LogOnPartial.cshtml code as follows works ...
@if(Request.IsAuthenticated) {
<text>Welcome <strong>@User.Identity.Name</strong>!
[ @Html.ActionLink("Log Off", "LogOff", "Account", new { area = "" }, null) ]</text>
}
else {
@:[ @Html.ActionLink("Log On", "LogOn", "Account", new { area = "" }, null) ]
}
Likewise, also changed the ActionLink parameters for Home and About menu items in _Layout.cshtml as follows ...
<div id="menucontainer">
<ul id="menu">
<li>@Html.ActionLink("Home", "Index", "Home", new { area = ""}, null)</li>
<li>@Html.ActionLink("About", "About", "Home", new { area = "" }, null))</li>
</ul>
</div>
The links appear correct and work now ...