Windows 7 - multiple programs with conflicting sound output
Driver type ASIO Audio device ASIO4ALL v2


Aha, there we go. ASIO is designed to give only one program at a time access to the audio hardware. As I said, this is in principle a good thing, because it ensures the DAW can run trouble-free and without overly long latency or crippled sound introduced when the OS tries to combine the audio from different programs so some composite that's then usable for even the worse hardware that can be assumed. However, for just testing out the program, learning features etc. none of this is really a concern, so you might as well use one of the non-professional alternatives. Microsoft DirectSound should always work.