Strange issue with SQLite.Interop.dll in VS unit testing

I have a very strange issue with SQLite.Interop.dll in VS unit testing:

I have VS 2015. I use System.Data.SQLite and I have got it trough nuget. My tests are normal MSTests.

Whenever I run all my tests, all tests that depend on SQLite fail with "Unable to load DLL 'SQLite.Interop.dll': The specified module could not be found".

When I then retest only th failed tests (thus those depending on SQLite) they all pass.

Why is this?

Any ideas? If any additional info is needed, I'm happy to provide that!

Thanks,

Michiel