You might want to look at
these Wiki pages if you haven't done so already.
For one thing, you have:
Sub Activity_Resume
EditTextResultDescription.Text = strResultDescription
End Sub
The link above explains why Activity_Resume is not the correct place for that code.
Another thing is that you said that you are not losing data when you press the Back key and return. While it may be possible that this happens on your device, I've never heard of one which acts like this and even if yours does, most don't -- they WILL lose the data.