Why VS 2012 removes files from my destination directory?

I have seen answers to similar questions but I still don't understand this... I have scripts that place all dependencies into a common BIN directory, which is outside all the projects directories.

solution.snl
BIN
ProjectAFolder
ProjectBFolder

All projects reference everything from BIN and they build into BIN. This way builds are faster and SO MUCH CONFUSION is avoided, among many-many other benefits. But why the heck VS removes some unreferenced files from bin?! I have a ThirdParty.dll that references other files (so dlls have to be in the same folder with ThirdParty.dll). When I rebuild these other files are deleted! What a bright idea! Or is it a bug?

My build complains like so if I make the files read only: 43>C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(3969,5): warning MSB3061: Unable to delete file "C:\Projects\GITBranches\trunk1\EDA\bin\tibrv.dll". Access to the path 'C:\Projects\GITBranches\trunk1\EDA\bin\tibrv.dll' is denied.

and this is the line in Microsoft.Common.targets that tries to do this:

<!-- Delete the orphaned files. -->
<Delete
    Files="@(_CleanOrphanFileWritesInIntermediate);@(_CleanOrphanFileWritesInOutput)"
    TreatErrorsAsWarnings="true">

  <Output TaskParameter="DeletedFiles" ItemName="_CleanOrphanFilesDeleted"/>

</Delete>

Does anyone know how I can win?

Thank you

Solution

I think your best bet is to have third party files stored in a separate directory, e.g. A Lib directory.

Then you can copy them to your bin directory as part of a pre build event perhaps?