Shell Programming and Scripting

Hi, I am very new to shell scripting.
I have a script called "RunDMol3.sh" which takes a directory name as input parameter, process somthing using files in the folder and writes output files in the same folder. This is a very heavy job and takes about 1.5 hrs.
When I run in manually the script runs well and output files are generated successfully.
There are about 64 such directories. So I wrote a script called "serial_script.sh" that would go through all such directories and execute "RunDMol3.sh" one after the other.
This script is executed as

nohup ./serial_script.sh &

But I dont know why after running some few jobs the linux system crashes! Are there any memory related issue? Or am I missing something? how can i find the reason of system crash? Below is the script I am running. Thanks in advance. Below is the script.sh I am running.

#! /bin/bash
exec > log.txt 2>&1
echo "Starting to run all jobs"

cd directory1/
RunDMol3.sh directory1
cd ..
echo "1 of 64 jobs completed (directory1)"

cd directory2/
RunDMol3.sh directory2
cd ..
echo "2 of 64 jobs completed (directory2)"

cd directory3/
RunDMol3.sh directory3
cd ..
echo "3 of 64 jobs completed (directory3)"
.
.
.
.
cd directory64/
RunDMol3.sh directory64
cd ..
echo "64 of 64 jobs completed (directory64)"
echo ______________________________________
echo "Atempted to run All jobs"

First create the log file for the following.
nohup ./serial_script.sh > /tmp/serial_script.log &
Put more debug statement.
Check this log after which directory the system goes down.

Also you can check the system performance using "w". It will show the load average. This cmd will work in sun os.

Thanks
Sarwan

Are you getting a core dump when the system crashes?