When I started reading this thread i was thinking alternator too.

Had a similar problem about a year ago.

One of the three wires into the alternator is a feed from the ignition live.

In effect it's a signal wire to tell the alternator to output the current its producing.

This wire was cracked in my case and would result in a very similar intermitent problem.

When the battery eventually died, i would get very similar results.

(incedentaly because the alternator is not

"switched on" you dont get the dash lit up like a christmas tree warning)

What moves me away from the alternator are a couple of things.

Firstly the car runs fine on just the battery until it is drained.

When it's drained the first thing that went for me was the power steering.

I would typically have about a quarter of a mile before the engine died.

Secondly i would be very suprised if the car would start again if the battery was discharged to the extent that the speedo/ignition stops.

I left a multimeter wired across ignition live and ground to show the voltage as i was driving

- could tell when the alternator was switching off.

This would at least tell you what the alternator is putting out.

If this still reads

~14v when your speedo goes, i would rule out the alternator

(subject to more knowledgable member happening by

)

edit to add: voltage would be

~11v if alternator is not working