Just an update on this problem.
By moving the call above some of the other code, I'm able to eliminate
this
problem.  However, the algorithm does not let me move the line.
But, when looking at the code in dissasembly view, there is no
difference in the call.  Therefore, I believe that the error
may be a side effect of memory or register usage in the 
preceding calls.  Still not sure.  Any help would be appreciated.

Thanks,
Tony