Posted for "Gerard O Connell" <goconnell@dodo.com.au>:

 Ok, I did I fly past today and the tower confirmed that the nose gear door on
my 320 was indeed open as I expected and thus causing the "buzzing" noise I
had experienced in flight.
 
 The nose wheel is still retracted as are the mains and their gear doors..this
suggest that there is plenty of hydraulic pressure in the "up" line.
 
 Can anyone tell me why the nose gear door alone would hang open?
 
 Regards
 
 Gerard