Hi I have a ULTRA ENTERPRISE 2 machine. The system won't allow me to log in. When I use the root /root-password to login at CDE graphics screen , it says invalid user shell. I have not set up any other account here so I don't know whether this problem is only for root user.Whats the next step ??/

Have you ever changed root's login shell?
Generally, you shouldn't do this,
and if you can't resist the urge, make sure it is a statically linked shell if you have separate filesystems for / and /usr

maybe you changed the root password but you forgot?
you want to boot from cdrom to single user mode, remove the encrypted password in the shadow file, boot up and try again first..

I did not change the root password. This problem happen after I gave a rm command and now I am thinking whether this command deleted any important files because my command format was wrong. The other thing is cdrom drive is acting up. I wanted to install solaris 9 to this machine but when I placed the solaris 9 installtion cd 1 and close the cd tray, it closes and next moment comes out. I don't know whats going on here.

So are you trying to recover or re-install?
"rm" is a danderous command and must be used with caution!
anyway, try removing the cdrom. drop the system to ok prompt and probe your devices. set-defaults and reset-all at OBP.
power-off the system from ok prompt/OBP. Power on and insert your cdrom into the drive again and try

Still the problem remains. Something interesting is happening here. I dropped the system to OK prompt and gave boot disk1 -s command. In the login prompt when I enter the root password , the system accepted it and displayed "NO SHELL" and continued loading .then it came to CDE and prompted me to enter username and password. When I tried here root /root-password combination a message appeared saying " INVALID USER SHELL. LOGIN REJECTED" I cant close this message and cant proceed . Whats going on here. please help

you should "boot cdrom -s"
then in the maintenance mode, mount /dev/dsk/cxtxdxs0 /a
vi /a/etc/shadow -> remove away root's encrypted passwd
then umount /a
reboot the system