user login problem & Files listing problem.

1) when user login to the server the session got colosed. How will resolve?
2) While firing the command ls -l we are not able to see the any files in the director. but over all view the file system using the command df -g it is showing 91% used. what will be the problem?

Thanks in advance.

there may be hidden files.Did you tried ls -la(listing all files including hidden files)??

And for session closing did you tried with some other user, Because some times if the user's password expired this will happen.