change security password does not work

[Thomas]

Mozilla 0.9 final on Win98SE: I have successfully created a security 
password (works fine!), but somehow I can not change this security 
password anymore.
I cleared all sensitive information and stored the sensitive information 
from the beginning again, but the security password needs still to be 
the one I chose first. I see no way to delete or change it...

HELP!
Thomas