Alternator caused speedometer to fail...?

[98civic98]

Hi - I own a 98 Honda Civic with about 123,000 miles. About 6 weeks ago, I was driving about 50 mph and all of a sudden the speedometer went from 50 mph to 0. I was still able to drive until I came to a full complete stop. There, the car wouldnt start; after several hard cranks, I managed to get it to start and drove to a nearby autoparts store to replace the battery.

No problems until few days ago when car stopped completely again at a red light, managed to get it to start and this time decided to change the alternator.

Now the car is dead at the driveway and decide to get opinions on this forum before I bring it to a auto place so at least I have a clue of what to tell the mechanics.

Could it be the Speedsensor thats causing the car to stall or maybe the alternator I replaced is defective ??

Thanks

[98civic98]

Mechanic replaced the ignition switch today; the switch was burned out due to the alarm system. It was the primary reason why the speedometer drop from 50 to 0; thus causing the car to stall. Feel a lot safer now.