[VS2010] Debug all projects in the solution simultaneously?

I have a solution consisting of 2 projects, the main project with a UI and a "helper exe". When I click debug, VS builds both projects, then copies the helper exe to the debug dir of my main app and then starts debugging my main app. But if the helper exe gets an exception while the main app is using it, it just crashes.

Have I done something wrong? Is it possible to debug that helper exe at the same time as the main exe?

I suppose it is not since the helper exe isn't started with the main exe, but later on in the application...