Re:EZdrummer multitrack problem HS7
ez drummer is much higher CPU usage than any synths available in SHS7, so latency is going to show up in the higher resource usage softsynths if you don't have a recording soundcard with low latency drivers.
when you click play on the transport and nothing moves, that could be that you have already hit the dropout threshold for the audio engine.
multi output from softsynths was a known bug in the initial release of SHS7. it is fixed by downloading and installing the update.
to fix your problems you need to install the SHS7 update and to resolve the latency/dropout issues, you need to purchase a recording soundcard. there are recommendations on my website.