Could not load file or assembly bug in Visual Studio 2010

Update: The answer I made on this topic back for VS2010, has continued through the subsequent versions 2012, 2013, 2015, 2017, 2019 and now 2022.

Visual Studio 2010 does not honor the Copy Local setting on a referenced DLL unless you set it to false and then back to true.

By default the XML looks like this:

<Reference Include="DevExpress.SpellChecker.v11.1.Core">
  <HintPath>..\References\DevExpress.SpellChecker.v11.1.Core.dll</HintPath>
</Reference>

Following the simple step above sets it correctly, which is then honored by MsBuild and the DLL we be included in the deployment:

<Reference Include="DevExpress.SpellChecker.v11.1.Core">
  <HintPath>..\References\DevExpress.SpellChecker.v11.1.Core.dll</HintPath>
  <Private>True</Private>
</Reference>

A nasty bug. By default the Copy Local should be set to False in the properties window, since the build treats it as such.

To reiterate: To fix, change the Copy Local property to False then save your project. Then revert to True and save the project again.