App crashes Iphone

[evesake]

When in 3G network opening the app and then continue switching 3G network off (more precisly: switching "roaming" off) while the app is in the background the app freezes when going back in and then the Iphone freezes - not even the "taskmanager" is working - after about 5 minutes the app crashes and the iphone is responding again ... I experienced this multiple times.