I have the feeling in my gut that .NET support for EiffelStudio has been let lapse into "worked once, some time ago on a single test machine for .NET 1.1".

I have additional material which may or may not be related.

When I do get a .NET project loaded - and can see the Assembly folder at all, there are many classes that are not compiled - they are grey in the GUI.

When I selected one of them (usually the first one I select), I get an error message that "file c:\Windows\Microsoft.net\framework\v2.0.50727\System\ does NOT exist". (example was ARGUMENT_EXCEPTION - from System.ArgumentException in mscorlib.dll)

There are two issues here: (i) The version of .NET specified when starting the project was the 1.1 version; and (ii) there is no "system" subdirectory or file in any of the .NET frameworks.

Once I have successfully loaded the interface view of any (non-grey) Eiffel class in the Assembly list, this error message is no longer shown - although the title bar text of EiffelStudio changes to:
"APP_DOMAIN_UNLOADED_EXCEPTION in cluster mscorlib (not in system) located in "c:\windows\microsoft.net\framework\v2.0.50727\System\"

Which in fact does not exist. mscorlib.dll can be found in two places only:
framework\v1.1.4322\mscorlib.dll 15Jul2004 2,138,112
framework\v2.0.50727\mscorlib.dll 24Aug2007 4,444,160

And this despite unselecting the "use latest version" - actually it doesn't seem to matter - BUT that could be a caching of the initial compilation of what .NET assemblies it did find on install.