A common error is to pass the object where the address of the object is
needed.
For example, 

<PRE>
	MPI_Status status;
	...
	MPI_Recv( ..., status );
</PRE>	
is incorrect; it must be
<PRE>
	MPI_Recv( ..., &status );
</PRE>

This is also true for buffers, and is a common error when passing single
element buffers.  For example,

<PRE>
	int value;
	...
	MPI_Send( value, 1, MPI_INT, ... );
</PRE>
is incorrect; it must be
<PRE>
	MPI_Send( &value, 1, MPI_INT, ... );
</PRE>
