[Jack-Devel] The playback device hw:0 is already in use

I am new to jack and trying to setup Jack2 on Ubuntu 17.10 on a Dell laptop 15-5570 that uses a Realtek ALC3246 sound device. It is basically working ( I am testing it with simple_client and latent_client) but I think that I am doing something wrong as the first time I use it after booting the laptop  I get the error. "ATTENTION: The playback device "hw:0" is already in use. Please stop the application using it and run JACK again"  followed by lots of "Cannot connect to server socket err = No such file or directory" "Cannot connect to server request channel" fuser -v /dev/snd/pcmC0D0p shows that it is use by pulseaudio. However the 2nd and subsequent runs of the jack example clients work just fine without any error. Thanks for any suggestions or help Tim.