Quitting Amazon Kindle Fire App

I have my app out on Android and quitting works as it should. After submitting to Amazon Market, the app no longer closes properly (and also has issues opening again).

Firstly, pressing the back button brings up the exit menu as it should but when clicking "Yes" the app does not close. I call Application.Quit(); when yes is pressed but it just closes the dialogue box and continues with the app.

If I press the home button it goes back to the Kindle home screen and if I try to reload the app, it loads and closes within about 1 second. If I retry to open it, it opens properly.

These two issues are what has made my app fail to go on to the market so as soon I get them sorted, it should be available.

Has anyone had these issues before or do you know of a different way of Kindles handling opening/closing apps?

Thanks