ASP.NET : why is my website serving Default.asp instead of Default.aspx
<p>my "hello world" ASP.NET application works fine in debug. However, after I publish, I have issues :</p>

<ol>
<li><p>where do I control whether I want my website to serve Default.aspx or .asp as default page ? When I debug, it is calling Default.aspx with no problems, but after publish, it seems to request Default.asp</p></li>
<li><p>why do I get this error when I request Default.aspx manually ? (in browser)</p>

<p>The XML page cannot be displayed 
Cannot view XML input using XSL style sheet. Please correct the error and then click the Refresh button, or try again later. 
A name was started with an invalid character. Error processing resource 'http://localhost/slidenet/default.aspx'. Line 1, ...</p>

<p>&lt;%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" %>
-^</p></li>
<li><p>if I don't request a page, it will call my Default.asp that I created on purpose, and again, same error :
The page cannot be displayed 
There is a problem with the page you are trying to reach and it cannot be displayed. </p></li>
</ol>

<hr>

<p>Please try the following:</p>

<p>Click the Refresh button, or try again later.</p>

<p>Open the localhost home page, and then look for links to the information you want. 
HTTP 500.100 - Internal Server Error - ASP error
Internet Information Services</p>

<hr>

<p>Technical Information (for support personnel)</p>

<p>Error Type:
Active Server Pages, ASP 0221 (0x80004005)
The specified 'Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication1.Default" ' option is unknown or invalid.
/slidenet/Default.asp, line 1</p>

<p>Browser Type:
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E) </p>

<p>Page:
GET /slidenet/Default.asp </p>

<p>Time:
11 January 2012, 14:00:02 </p>

<p>More information:
Microsoft Support </p>
