Rejoin the machine to your domain.
Below is an example of the command:
/opt/quest/bin/vastool -u <adadmin> join -f <yourdomain.com>
Run the following two commands and verify that they are returning the same keytab file name:
/opt/quest/bin/vastool inspect libdefaults default_keytab_name
/opt/quest/bin/vastool ktutil list | head -1
If ktutil is returning a different keytab this could be caused by the KRB5_KTNAME variable set in your environment. Remove this environment variable or correct it to refer to the correct keytab file.