problem to login after upgrade samba

[nico at net-products.nl]

Hello,
I have a strange problem:

I did an upgrade from linux 7.0 to 7.3, using the upgrade option during the
installation.

Therefore samba is upgraded from 2.0.7 to 2.2.3a-6

After that users could not log in anymore, using samba. They get in
windows98 a "invalid password" message.
When I try to login with smbclient, using smbclient //localhost/root -U
username, I get NT_STATUS_WRONG_PASSWORD

I know for certain that i use correct passwords

But when I add a new user, samba works fine!
And on top:
There is one "old" username that works, then rest is not

I tried to upgrade to samba-2.2.7a-1
I tried to downgrade to the old version
I tried to delete old users and to add them again
I tried to reinstall 2.2.3a like
https://listman.redhat.com/pipermail/valhalla-list/2002-June/003948.html

I am out of options

Please help .... !