Why do I need to append "/default.aspx" ? Is this a Sharepoint or IIS issue ?

Win2003 SP1, two Sharepoint front-end serves, NLB, mappings extended
accordingly in Sharepoint.

If I do:
http://portal.mydepartment.company.org

I get "page under construction" error. This behavior is sporadic, sometimes
it browses OK.

Then I append:
http://portal.mydepartment.company.org/default.aspx
It works all the time.

I took one node down at time, the behavior is the same for both nodes. In
the "Default Website", I look into "Documents" tab and I see that
"default.aspx" is listed there (on the bottom). I then attempted to move the
"default.aspx" up. Problem persists.

Can someone there explain what could be causing this and how to solve ? I
want to type http://portal.mydepartment.company.org only, not append the
/default.aspx.

Note:I will also post in the IIS group.


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