Thank you Grey Cat,
I did what you told me to, but the package still fails.
the only way i can avoid the failure is to change the 'credential' password under security of the database.
I guess i did not make it clear
I found that whenever the user's password is changed in the windows operating system, i have to change the passward in the SQL server credentials too otherwise it will fail the package scheduled under the Sql Agent jobs.
My case is - one of our system administrators just went ahead changed the password without telling me and all my packages failed, i had to let him reverse back the password (or i could have just changed the password in SQL security - credentials)
And I wanted to know if there is another way to avoid this troublesome.