TeamCity - The process cannot access the file * because it is being used by another process

Question

I'm using TeamCity to build and run my MSTest project.

One job is responsible for building the project, once it has finished it triggers a second job responsible for running the compiled project using MSTest.

The problem is that when the second job is triggered almost immediately the following error is displayed and the job fails:

Starting: C:\...\JetBrains.BuildServer.NUnitLauncher.exe
...
...
...
The process cannot acces the file 'C:\BuildAgent\work\{identifier}' because it is being used by another process.

It seems that the job fails even before MSTest is invoked.