Other than root user .Normal user is unable to create files

UNIX for Advanced & Expert Users
1

Hi all,

  I am using Sun Solaris 9 .In this system normal users unable to create files from the command line.I added these users in bin,adm and even root group i found them unable to create a file.
2

Mess.
Does it have anything to do with root account expiration?
Did anyone say "It does not work" does not work.
OS? filesystem mounting? is the filesys full?