Curious FF 1.5.0.3 behaviour regarding passwords

Hi all,

I've upgrated my portable Firefox to 1.5.0.3.
I've copied then my orig profile from the old version
into the new version within PortableFirefox\Data\profile.
Everything works fine (bookmarks, extensions...) except
my passwords - Firefox doesn't recognize my old passwords
anymore (I've copied the whole profile including signons.txt
and key3.db).
In case to post here this topic I had to register to this forum
and Firefox saved (after asking for it) my portableapps.com-forum
password without any problem - now I can see it under
'Options->Passwords->View Saved Passwords' as the only saved password.
When I look into signons.txt all my old passwords are there
(inkl. the new portableapps.com entry)!!!

What can I do???
I would really appreciate any hint or idea

Regards
Artur