[Biturbos4] Either odd no-start problem or the world record for broken ignition switches - HEEEEELLPP!

[Grant]

Happy Thanksgiving all. I hope you all enjoyed the holiday.

Maybe there's some good in the list/site going down.  I learned more in 
the interim.

This is re; an A6Q 1995 (C4) auto.  Over the last <2 years, 3 ignition 
switches have been replaced.  The original for the "non return to 
start" bugaboo, and two more for a different problem - the car would 
crank but not start, or crank-catch-die.

This weekend #4 was replaced.
This is getting to be a problem, and my mom (the owner/driver) is 
getting scared to drive her car.

Symptoms:
a) car cranks great
b) when it does run (its intermittent) it runs great. Might stall very 
occasionally.
c) no pre-run of fuel pump in "run" position
d) no power to fuel pump/injectors/coil (e.g.: it is not a specific 
problem in any one of those subsystems)

Its pre-OBDII so I have not pulled codes.
I've checked with Audi (field support engineering - called a friend at 
home) and this car does not have an immobilizer, at lest not one that 
they think works this way.

This weekend, after two prof mechanics were stumped, and after I spent 
several hors looking over ECU wiring, harnesses, etc., I put a new 
switch in and all was right in the world. Starts and runs perfectly.

So what could make switches die on 3-4 month intervals, after the 
original going 8+ years?

Thanks all!

Grant