Unexpected Crash when integration (maybe)

Hi guys,

Base on the example of in.packing, I am trying to do a packing similarly.
Different from the example, I use pair style of gran/hooke/history/stiffness instead. I don't think it would be problematic but the system crash down when it came to the nve integration,
Here is the output of the screen:

LIGGGHTS 1.4.4 based on lammps-10Mar10
Created orthogonal box = (-1 -1 -1) to (2 2 2)
1 by 1 by 1 processor grid
0 atoms in group upper
0 atoms in group lower
0 atoms in group total
Fix particledistribution/discrete (id pdd1): distribution based on mass%:
pts1: d=1.000000e-02 (max. bounding sphere) mass%=100.000000%
Fix particledistribution/discrete (id pdd1): distribution based on number%:
pts1: d=1.000000e-02 (max. bounding sphere) number%=100.000000%
Particle packing insertion: trying 802.140913 particles once
Particle packing insertion: trying 802.140913 particles once
DNUM 3
DNUM 3
DNUM 3
Setting up run ... (system crashed down here)
Killed

Below is the script I used: , please help me out, thanks!!
# v_0_2 3D simulation of Direct Shear Box Test, to be completed
# By Anson Liang, lzefeng@gmail.com Feb 17, 2012
units si
boundary m m m

atom_style granular
atom_modify map array
newton off
communicate single vel yes

#lattice bcc 0.002
region bigbox block -1.0 2.0 -1.0 2.0 -1.0 2.0 units box
create_box 1 bigbox
timestep 0.00001

neighbor 0.002 bin
neigh_modify delay 0

#=====Define simulation space and the upper lower boxes======
region upper block -0.15 0.15 0.08 0.16 0.0 0.07 units box
region lower block -0.15 0.15 0.0 0.08 0.0 0.07 units box
group upper region upper
group lower region lower
group total union upper lower

#=====Set properties for pair_style, no cohesion in this case======
fix normal all property/global kn peratomtypepair 1 5.0e9
fix tangent all property/global kt peratomtypepair 1 1.5e8
fix damping_n all property/global gamman_abs peratomtypepair 1 5.56e4
fix damping_t all property/global gammat_abs peratomtypepair 1 0.99e4
fix coeff_friction all property/global coefficientFriction peratomtypepair 1 0.5

pair_style gran/hooke/history/stiffness 1 0
pair_coeff * *

#======================random packing====================================
#*******set up walls to bound particles when packing *********
fix x_walls all wall/gran/hooke/history/stiffness 1 0 xplane -0.15 0.15 1
fix y_walls all wall/gran/hooke/history/stiffness 1 0 yplane 0.0 0.16 1
fix z_walls all wall/gran/hooke/history/stiffness 1 0 zplane 0.0 0.07 1

#distributions for insertion
fix pts1 all particletemplate/sphere 1 atom_type 1 density constant 2500 radius constant 0.005
fix pdd1 all particledistribution/discrete 1.0 1 pts1 1.0

#parameters for gradually growing particle diameter
variable alphastart equal 0.25
variable alphatarget equal 0.67
variable growts equal 50000
variable growevery equal 40
variable relaxts equal 20000

#region and insertion
fix insert_particles_upper all pour/dev/packing 75 distributiontemplate pdd1 vol ${alphastart} 200 region upper
fix insert_particles_lower all pour/dev/packing 84 distributiontemplate pdd1 vol ${alphastart} 200 region lower

#apply NVE integration to all particles that are inserted as single particles

fix NVE_integration total nve/sphere

#output settings, include total thermal energy
compute 1 all erotate/sphere
thermo_style custom step atoms ke c_1 vol
thermo 1000
thermo_modify lost ignore norm no
compute_modify thermo_temp dynamic yes

#insert the first particles
run 1
dump dmp all custom 350 dump.packing id type type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius
unfix insert_particles_lower
unfix insert_particles_upper

#calculate grow rate
variable Rgrowrate equal (${alphatarget}/${alphastart})^(${growevery}/(3.*${growts}))
print "The radius grow rate is ${Rgrowrate}"

#do the diameter grow
compute radius all property/atom radius
variable d_grown atom ${Rgrowrate}*2.0*c_radius
fix grow all adapt ${growevery} atom diameter d_grown
neigh_modify every ${growevery} check no

#run
run ${growts}

#let the packing relax
unfix grow
neigh_modify check yes
run ${relaxts}
#=======================End of packing================================

# to be completed