doOnlyOnce is just the kind of magic I was looking for.  With that and 
Bob's tip to look in the debug log I was able to corner the problem and fix it.

Thanks.

At 06:19 PM 12/27/01 -0500, Doug Way wrote:


>In this situation, I usually try the #doOnlyOnce trick with a halt.
>
>Use this code instead where you were trying to put the halt (which
>brought up the emergency evaluator):
>
>self doOnlyOnce: [self halt].
>
>This will just do the halt the first time, and then it can proceed
>through successfully the following times to open the debugger, etc.  See
>ProtoObject>>doOnlyOnce: for more details on how to "re-arm" the
>doOnlyOnce mechanism.
>
>Actually, this reminds me that someone posted an improvement awhile back
>to reimplement #doOnlyOnce as a method on BlockContext, but I don't
>think it had the right subject header to get harvested.  I'll dig that
>up and repost it.
>
>- Doug Way
>   dway at riskmetrics.com