http://developer.android.com/reference/android/app/Activity.html
"An activity can frequently go between the resumed and paused states -- for example when the device goes to sleep"
http://developer.android.com/training/basics/activity-lifecycle/pausing.html
You need to manage state using the Activity lifecycle methods, rather than trying to "set the activity not to recreate." Activitys are created/destroyed/recreated all the time, by design (and for the record locking to one orientation is also sort of a band-aid, dealing with state correctly will mean you don't have to do that either).
This question may help, the answer has an example of dealing with instance state: Saving Android Activity state using Save Instance State