Logging in via putty redirects back to the login prompt screen (Linux Fedora 8)

Hello Guys,
I am using Fedora 8 linux on virtual machine.
Till last day I can login to this server via putty with Root credentials without any issue.
Now suddenly I keep getting redirected to the login prompt screen after i input my root password. I input it over and over, and it always send me back to the login command prompt screen instead of logging me in and that is without any error.
Can anyone help me with this issue?
I am not an advanced user so if you can please detail your help, I would much appreciate. Thank you all for your time and patience!

Note: I am having only one user i.e. root user and in fedora having only command prompt(NO GUI).