A few people i know have had problems with these and other Alfas, they seem to be unreliable. A 156 spent more time being repaired in the first 6 mths of its life then it spent on the road. Was replaced though by Alfa. May be a one off but still have a bad reputation.
And search for the car and the reviews tell you of problems that are common with them. Saying that my mate bought one over 6months ago and has never had to have it in a garage and he uses it every day to commute 25 miles to work and at weekends to travel all over the country.