I have similar problems. For example, I tried to launch USAToday, the logo appeared and after several seconds, got me back to home screen. Same problem with Weatherbug (I went and got the Weather Channel and this works). Nook Book App opens books but when I press the icon to take me to the bookstore, I'm not able to connect to BN.COM and the app kicks me back to home page. (Kindle and iBook works.) The Bloomburg App, something I've used since the very beginning, stopped working too. My thinking is that all of these apps require a good internet connection, so I waited until I got home today and started using wifi, still no go on these apps.
I have closed all the apps in the multi-task bar. I have reset my iPad by turning it off and waiting several seconds and still these apps don't work. I would reinstall USAToday and Weatherbug but I do not want to uninstall NOOK or Bloomburg because I do not want to loose my books that I have bought nor have to re-enter the stock portfolio that I refer to everyday. Maybe I'll delete Bloomburg since I can't see this portfolio any way.
There has got to be a better way to figure out what the problem is and resolve these problems without having to uninstall anything and have to reinstall to get an app to work again.