This is my 3rd Sony Ericsson and it happened with my previous phones and now the current one too.
I have found that the charging plug which connects the charger after prolonged use, it seems to have a problem, it either does not connect 100% between charger and phone &/or the contact points have been eroded, therefore this problem.
However, once charged to full the phone does work. It may hang because of several "error, stop charging" waiting in queue. Just remove and replace battery and it should work fine.
Love Sony Ericcson
December 2009