I get the same problem intermittently. It would suddenly lose the network (Vodafone UK) and sometimes come back. That was on PR1.2 and also happens on PR1.3. To get it round it I go offline then normal mode from the power button. This gets round the problem (as there is no issue with network coverage) - but it is annoying. I was hoping it would have gone with the upgrade in firmware, but didn't (although not happening as frequently).