I have been trying to dive into WF this week based on some questions from customers, but was having trouble getting the WF designer to work in Orcas.  I upgraded to Orcas a few weeks ago after uninstalling VS2K5, but hadn't tried to run the WF designer since upgrading.  Since it worked in VS2K5, I figured it'd work here.  Ha.

Here's the first error I got:

The item "Properties\AssemblyInfo.cs" was specified more than once in the "Sources" parameter. Duplicate items are not supported by the "Sources" parameter.

OK - So searching around found a bunch of hits, but nothing that worked for me - they all applied to betas of VS2K5.  I traced this down to some entries in my csproj file:

<Import Project="$(MSBuildExtensionsPath)\Microsoft\Windows Workflow Foundation\v3.5\Workflow.Targets" />

When I dug into this, I found it pointing to a folder that didn't exist:

C:\Program Files\MSBuild\Microsoft\Windows Workflow Foundation\v3.5

OK - so I tried creating that folder and copying the 3.0 versions of those files into there.  Fat chance... It didn't work, but at least I got a different error:

Required filealink.dll with IAlink3′ could not be found.

Searching on that led me to a blog post by Sam Gentile that addressed my exact problem, which was brought on by a *different* problem.  In an earlier post, I outlined how I was able to get past an installation problem with Orcas by manually installing the v3.5 framework from my installation media.  The install was failing with some weird Installer error.  What I didn't know, is that the installer also installed a few hotfixes that my system (subsequently) never got.  Because of this, the Workflow Designer didn't function properly.

So, I installed those hotfixes (2 reboots required!) and ta da!!!  Now the designer is working, and all compiles OK.

Whew!  Several hours wasted on this problem and I still haven't gotten into the WF question I was asked!!!

PS - I'm running Vista Enterprise 64-bit on my Dell D820.  Not sure if any of these problems are related to this machine running 64-bit, but they might...