Strange problem with Users...

[Joutei]

Hey i have a very weird problem... when i want to run knoppix as a normal user, the screen is turns black, and returns to login screen. I have 2 users created (wuth root there are 3 users). When the problem appeard i have deleted those 2 normal users. After making those users again the problem is still appearing. Could You help me?

P.S I rather don`t want to reainstall knoppix.