What is your OS? What were you trying to run at the time?

Sunsolve shows the following - this may or may NOT be your problem:

This error is due to dtterm not being able to open /dev/pts/N (where N
is an integer). The reason they are unable to open this file is because
grantpt failed to change the permissions on the file. Grantpt failed
because the binary /usr/lib/pt_chmod is not setuid root. The permissions
on /usr/lib/pt_chmod must be 4111.

To restore the correct permissions to pt_chmod, use the following
command: (as root)

# chmod 4111 /usr/lib/pt_chmod

Also, make sure that /usr/lib/pt_chmod is owned by root and by the group
bin.