I recently had an issue with VS2010, C#, and .Net 4 where I could not use the namespace from my referenced assembly (call it AssemblyA). It is similar to the issue here.
I was able to correct the problem by setting AssemblyA to target x86 platform instead of Any Cpu.
My question is why did changing the platform target to x86 allow me to use the namespace from AssemblyA in my project?
I want to note that I was able to reference AssemblyA in other projects without changing the platform target. Also all of my references were project references.
EDIT: Apparently I am mistaken. It is not working even when changing to x86. Any ideas what could be causing this?
Update: All my projects are using the full .NET 4 profile.
EDIT:
After doing some testing I have some more information. When I switch between Debug/Release builds (Doesnt matter the order I switch) and do a clean on AssemblyA then I am able to use the namespace no problem. As soon as I rebuild AssemblyA then I can no longer use the namespace. It doesn't seem to matter what platform I am targeting.