I restored iPhone 3G to iOS 4.2.1 a then made JB with RedSn0w. Everything went successfuly but Cydia doesn't work. When I start cydia, it is stuck at screen with message"Loading" and nothing happens. It doesn't respond on any click (e.g. on changes tab, manage, etc). I tried to re-JB and restore once again but nothing helped. I received message that this version of Cydia is unsupported and I should update but I don't know how.