What happens to cursors in android when shifting between activities?

I have an activity where I have one list with database content. When I click something on the list it starts a child activity where it shows the text of that element.

When this was using only one table I could come back to the parent without a problem. Now I want to pick on a menu between 2 different tables to fill the ListView. It works fine and picks/fills the ListView with the correct table, but when I go to the new activity and try to come back to the main activity it crashes.

The only difference in the code is one if/else, and it loads correctly when you go there the first time, it only has the problem coming back to the activity.

Maybe this is a newbee question, but what can be the problem? I already spend hours on this without getting to a solution. I assume it can be something with the cursors as that is the part I understand less about.