Symptom :
When trying to change a password for a user on CentOS 5.5 I recieved the following error message :
"/usr/share/cracklib/pw_dict: error reading header"
Of course the password was not changed .
Solution :
Reinstall the cracklib-dicts package .
Run the command :
rpm -e cracklib-dicts --nodeps
Then run :
yum install cracklib-dicts
Now all is well .