Thank you for your reply.  I've added a Load method to my user control and
it does seem to address the problems I'm having.  Let me provide greater
details.

I've constructed a user control that contains only an axWebBrowser control
(the browser control completely fills or covers the user control panel).
This user control contains the following methods: ClearContents, SetContents
and Navigate.  Navigate does pretty much what you've outlined below.
ClearContents navigates to "about:blank" and SetContents navigates to
about:blank and within the captured DocumentComplete event writes a content
string into the HTML document.  I'm doing a lot of dynamic HTML creation and
the user control is an abstraction that helps hide the details of pushing a
HTML string into a browser.  Mostly this works very well except when Dispose
it executed.    ... as an example here is what ClearContents looks like:

       public void ClearContent() {
           m_browserAction = BrowserAction.Clear;
           m_browserState = BrowserState.Requested;
           object n = null;
           if (this.InvokeRequired == true) {
               this.Invoke(new NavigateBrowser(m_browser.Navigate), new
object[] { "about:blank", n, n, n, n} );
               }
           else {
               m_browser.Navigate("about:blank", ref n, ref n, ref n, ref
n);
               }
           }

In my application I make heavy use of the above control, and place it on
several panels in a tab control.  In my application I had to code this loop
in my application's Dispose method:
     // run thru all the tab pages so you don't get a dispose error (which
gets thrown if the BrowerControl doesn't get it's window shown
     for (int i = 0; i < m_tcMain.TabPages.Count; i++) {
           m_tcMain.SelectedIndex = i;
           }
If I do not touch all the tabs, then in the user control's dispose method
"base.Dispose(disposing)" throws a
System.Reflection.TargetInvocationException ("Unable to get the window
handle for the 'AxWebBrowser' control.  Windowless ActiveX controls are not
supported").  Initially in the browser user control, I called ClearContent
from within the Contructor, but on your recommendation I moved this call to
the Load method.  However, when I remove the "tab touch loop in the
application, I still get the TargetInvocationException throw.  After that
exception is thrown a couple of times I get a NullReferenceException
("Object Reference not set to an instace of an object") in "main" of the
application.

I can avoid this problem by creating a static bool in the browser user
control that ensures that the Dispose method runs only once regardless of
how many instances of the control exists.  However, doing this without
understand why isn't exactly appealing.  If I had to guess I would say that
some part of the AxWebBrowser is shared across all instances of the object
and that the first object that dispose of it, leave all the other instances
broken.

Thanks