Xperia Ray :: Starts Permanent Reboot When Crossing Border?

probably since the last Android Update to 4.0.4, my Ray with 4.1.B.0.587 starts self-actuated a permanent reboot loop whenever I am crossing the German-Austrian border and therefore reaching an Austrian (i.e. foreign) network.

The loop restarts whenever it reaches the point where it checks the SIM card and then starts with a Sony screen like when I switch it on. The loop can only be interrupted by removing the battery. OK, also by going back to Germany. I have full phone roaming authorization from my home network (vodafone), yet for data roaming I need to purchase day or week packages. Up to that Android update, all that worked perfectly, including tehtering.

So, in fact, I am currently not able to use my phone in foreign networks.