After upgrading my unlocked iPhone 2G from V1.1.4 to V2.2, my phone started 'hanging' periodically in DFU? (black screen) mode. I then have to hard reset (pressing 'home' and the 'power' buttons simultaneously for 15 seconds). This happens many times in one day. I've tried restoring it many times via iTunes 8. Should I downgrade back to V1.1.4 or iTunes 7, perhaps? PLease help!

Thanks for all the advice I got! :-( I think I solved the problem myself by restoring again to V 2.2, and then unlock with QuickPwn. But this time I didn't install Cydia, as I suspected that it was the problem. Firstly it would never upgrade due to errors in downloading, and secondly 'hanging' started when I upgraded from V1.1.4 to V2.2 and installed Cydia. It's been a week now, so, so far, so good.