It is not uncommon for an app to not function proper. This may have more causes to wich i'm going to explain the following to make you understand what it could be. This by all means does not mean it will lie within these cases.
This might be due to the lack of proper fundamental documentation on how to program / create / debug an application for the Playbook. Resulting in indie developers that attempt to make an app that will not function proper by not been tested enough. Therefore crashes on untested controls performed on the application.
It might also be an Andriod app that get ported. Sometimes a port just doesn't go through the right way and messes up somewhere in the middle. Leaving you with an malfunctioning app.
It's sad, but it's there. Andriod, Samsung's Bada, Windows Mobile and IOS have the same thing. Every OS has flaws when it comes to their apps. It is very common and there is very little RIM or the Playbook itself can do about it.