Rename secmod.db (secmod.db.old) in the Profile Folder in case there is a problem with the file.

You may have to rename cert8.db (cert8.db.old) as well.
Firefox will create new files.

Renaming/deleting secmod.db and cert8.db didn't work, I had to create a new profile as described at http://kb.mozillazine.org/Profile_Manager

"cor-el" answer woks like charm, tnx man.... //Cut Creator

My solution was (Firefox12, portable version, WinXP, without install rights):

1. on the Firefox\data\profile folder: Right click, Security, Advanced, select myself,

2. Uncheck Inherit from parent permission... (Copy) then

3. Press Edit, and set full control, Apply onto: This folder, subfolders and files, Apply

4. Delete from profiles folder: cert8.db, key3.db, secmod.db

Finally: Start Firefox

I have this problem but I do not find the files referred to in searching my Mac. Even if I removed and re-install FireFox, still can't get it to work - that long security error keeps coming up.

See this article -> Fix the "Could not initialize the application's security component" error message

Check and tell if its working.

I had the same problem and I resolved it by deleting the cert.db file. Remember that you had to close the firefox when deleting the cert.db file and read and should have write permissions on cert.db file.

The following page helped me :

Could not initialize the application's security component