A problem with memory deregistration

Hi,
Using mpich-1.2..3 we get a problem with memory deregistration
using the synchronous send (MPI_Ssend) of a datatype with size >16KB.
The problem doesn't appear either using MPI_Send or sending contiguous
buffers.
 
For example running the following code:  

#include "mpi.h"  
#include <stdio.h>
 
int main(int argc,char **argv)  {
    int myid, namelen; 
    char processor_name[MPI_MAX_PROCESSOR_NAME]; 
    MPI_Status status; 
    float v1[3000],v2[3000]; 
    int ArrayLength[2]; 
    MPI_Aint ArrayOffset[2]; 
    MPI_Datatype ArrayTipi[2] = {MPI_FLOAT, MPI_FLOAT}; 
    MPI_Datatype dtype; 
 
    MPI_Init(&argc,&argv); 
    MPI_Comm_rank(MPI_COMM_WORLD,&myid); 
    MPI_Get_processor_name(processor_name,&namelen); 
 
    ArrayLength[0]=ArrayLength[1]=3000; 
    MPI_Address(v1, &(ArrayOffset[0])); 
    MPI_Address(v2, &(ArrayOffset[1])); 
    MPI_Type_struct(2,ArrayLength,ArrayOffset,ArrayTipi,&dtype); 
 
    fprintf(stderr,"Process %d on %s\n", myid, processor_name); 
    if (myid == 0) 
        MPI_Ssend(MPI_BOTTOM, 1, dtype, 1, 99, MPI_COMM_WORLD); 
    else
        MPI_Recv(MPI_BOTTOM, 1, dtype, MPI_ANY_SOURCE, 99, MPI_COMM_WORLD,&status); 
    MPI_Barrier(MPI_COMM_WORLD); 
    MPI_Finalize(); 
}     

we get the following message:
 
Process 0 on n1
Process 1 on n2
Unexpected state for clear_interval:zone=0x8000000:benice=1,s=0xe4,e=0xeb,i=0xe5,j=0xe5,registered[j]=1,refcount[j]=1
9305 vvvvvv dump_reg_cache vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
regcache.c:132: failed assertion: "0".
9305 from 0x8000000 length 0xe4000,registered=0 refcount=0 
9305 from 0x80e4000 length 0x7000, registered=1 refcount=1
9305 from 0x80eb000 length 0x315000, registered=0 refcount=0
9305 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 

probably because there is an attempt to deregister a region
with refcount !=0 

Thanks in advance
Marco