it's a small world!p.s. there some garage called "Dexol" said: there other 2002 aston 5speed gearbox got the same fault and they change some parts of the gearbox (the dealer asked to change the hole gearbox).
that was a 2003 actually.. and it's right outside my place getting some work done
p.s: when your engine is cool, check the coolant and see if it's mixing with transmission fluid
might be a long shot, but it's worth a look