I've been trying to install the December CTP of WinFX and I've been having
problems getting it all to work. I've tracked down at least some of the
problems and wanted to report them here. One symptom of the problem was that
if I browsed to a website that hosted a XBAP application (e.g.
http://www.valil.com/winfx/Valil.Chess.WinFX.xbap) it didn't recognize it as
a WPF application and asked to download it instead.



The problem is that when the WinFX runtime components are installed, they've
have the access rights in the registry set incorrectly. I normally run WinXP
as a non-administrator user. I rarely use the Administrator account and
elevate my account permissions temporarily when necessary to administrator
rights using MakeMeAdmin (see
http://blogs.msdn.com/aaron_margosis...24/193721.aspx if you
want details). This works quite well for almost everything.

When WinFX installs, it (correctly) creates a MIME type in this registry
key:
HKEY_CLASSES_ROOT\MIME\Database\Content Type\application/x-ms-xbap
and gives Read/Write permissions to the administrators and Read permissions
to users. The problem is that when the installation registers these file
extensions and handlers:
HKEY_CLASSES_ROOT\.xbap
HKEY_CLASSES_ROOT\Windows.Xbap
HKEY_CLASSES_ROOT\Windows.Xbap.1
it gives Read/Write permissions to the administrators and NO permissions to
users. So when you try to run the WPF application using Internet Explorer as
a non-administrator it can't read any of the registry keys and considers the
..xbap file an unknown file type. Running as an administrator or manually
adding Read permissions for users to the above keys solves the problem. I
suspect there are many other issues besides this specific one when running
as a non-administrator though because of permission settings not being
correct on other keys (I'm new to WPF so I'm not sure where else to check
yet).

Note that I've tried installing with the Local Security Policy for "System
objects: Default owner for objects created by members of the Administrators
group." set to both "Object Creator" and "Administrators group" and the
effects seem to be the same.