[TYPO3-english] BE login problem after upgrade to 4.3.1

[Barbara Johansen]

Hi.
I just upgraded from 4.2.11 to 4.3.1. (PHP Version 5.2.5)
My admin user can no longer log into the BE.
I created some new ones with Install-tool, none could login

"Your login attempt did not succeed
Make sure to spell your username and password correctly, including 
upper/lowercase characters."
.
The old non admin users have no login problems. But creating a new non 
admin user gives the same problem: no BE login.
I promoted an old user to admin (in the database) - now this user can 
login the BE as an admin.
That means: New users and old admin users cannot login the BE.

I tried several settings:
[BE][lockIP] = 0
[BE][enabledBeUserIPLock] = 0
[SYS][doNotCheckReferer] = 1
/[SYS][lockingMode] = disable/
$TYPO3_CONF_VARS['SYS']['devIPmask'] = '*';
SET SESSION sql_mode='MYSQL40'

Nothing seems to help.
Any suggestion will be appreciated

Greetings
Barbara.