Problem: Map image does not display in a .NET web application
A Microsoft .NET web application created by ArcGIS Server or ArcIMS does not display properly in Internet Explorer. The main map image does not display but the banner, toolbar, and frames do display when accessed as:
The web application displays correctly when accessed as:
This problem only occurs when loading the application with Internet Explorer. Other supported browsers such as Netscape and Firefox do not experience this issue.
This problem occurs when the host name of the machine serving the web application contains an underscore character. Host names cannot contain underscore characters due to a limitation of Domain Name System (DNS) and Active Server Pages (ASP).
From the Microsoft Support website:
For more information, see the link in the Related section below.
Solution or Workaround
Change the host name of the web server computer serving the web application to a name that does not contain underscores.