<p>I have tried, 'PreviousPage', 'PreviousPage.IsCrossPagePostBack' 'Page.previousPage', page.title</p>

<p>It causes the client to stop rendering the page after this line.</p>

<p>simple example</p>

<pre><code>protected void Page_Load(object sender, EventArgs e)
{
response.write("I can see this");
string test = PreviousPage.IsCrossPagePostBack.toString(); //Any page call Causes client rendering to freeze
response.write("But i cant see this");   
System.Windows.Forms.MessageBox.Show("However i can see this,proving that the server is still running the code");   
}
</code></pre>

<p>Anybody Please, any ideas? </p>

Have you checked PreviousPage for null?
From
msdn
:
The PreviousPage property is a null
  reference (Nothing in Visual Basic)
  when the user requests that page
  directly from the server.
Also -
```
MessageBox
```
in a web form,
not
a great idea... perhaps use the inbuilt
trace.axd