MD,discover,H-bond,help

[MCCCM : at : jazz.ucc.uno.edu]

 Dear Netters,
 Could you please try to help a friend of mine with the following:
     I am trying to run Discover with Amber force field.
 It seems that the minimization makes my initial B_DNA_Duplex
 structure (7 nucleotide-pairs) fall apart. What should
  I do to avoid that? Is there a way to avoid the hydrogen bonds
 get apart?
 Here is the input file. I can send you the .car
 and the .mdf files if you wish to take a look
 -----------------------------Input file-----------------------
       overlap = 0.01
       cutoff = 12.000000
       cutdis = 11.000000
       swtdis = 1.5
       begin simulation
      *    add-automatic bond torsion valence out-of-plane
       reduce
       scale 1-4 parameters by 0.500000
       set dielectric  = 4.000000*r
       Minimize
      *    no cross terms
      *    no morse
      *    for 10000 iterations
      *    using conjugate gradient
      *    until the maximum derivative is less than 0.001000000 kcal/A
       end
 ------------------------------------------------end of input file
 Any help is highly appreciatted.
 Thanks,
 Monica