Music stops when open apps
I have an iPad 2 and iPad 3. Both have the same issue. I will start playing music using the music app (standard app which came with the iPads). Music plays fine. I will then open an app such as Safari or iBooks. Sometimes the music will continue to play. Other times it will stop. I can't seem to reproduce the experience the same way each time. For example, I can open the music app, start the songs playing and then click on home button to open Safari (or iBooks). When I do that, the music will stop.
I am using the latest iTunes, have my iOS up to date etc. I regularly sync to my MacBook Pro which has Mountain Lion.
I suspect I am simply doing some step in the incorrect fashion.
Any suggestions oir advice are welcome.
iPad, iOS 5.1.1, iPad 3