can someone help me out?

i read other people (pete) have had problems with the geisha light like me. i took it apart and regreased it like i was supposed to (and assembled it correctly), but it sometimes doesn't catch and once i pedal hard and stop pedalling i hear this horrid bang/click. what's up with this thing?

I say take it apart again and make sure everythings ok... or send it in for another and say its defective.

The clicking that you are hearing are those little balls on the spindle with the little nuts around them.  They are spring loaded.  They may be a little tight.  If they are too tight they tend to hold the clutch in place which allows it to skip.  A friend of mine was having the same trouble with his older Geisha hub.  He just took it apart and used some WD-40 and some all in one oil and made sure that those little balls were working freely.  Regreased and put it back together and it now works perfectly.  Still clicks but as others have said it gets better with time.