panic: Bus error -- stopping myself...

[Michael Friedlander]

My code is solving a sequence of least-squares problems via

   x = A \ b;

where A is dense and tall and getting wider by one column at each  
iteration.  After about 50 iterations, I get the error "panic: Bus  
error -- stopping myself..."

How do I begin to diagnose the source of this problem?

I'm running Octave 3.0.0 on an Intel MacBook Pro running Leopard  
10.5.1.  But I also confirm a similar error on a Linux box.

Michael