adstrtal.sh: exiting with status 1

This is one of the messages i got while starting APPS tier of e-business suite.
I am new to this thing, so checked a few things. Logged onto the database , and tried to connect with apps user which was quite successful. Then i realized that may be listener is not up, and that was the culprit. So i started listener using command adalnctl.sh start PROD and once again started Apps tier which worked now!!

Alert tab of oracle Grid Control

We have grid control installed in one of our setups. This is quite useful as you can register all your databases here and monitor them from a centralized control. One of the good things i like about this is the alert tab. By clicking on the alert tab you can easily see all the errors coming in any of the databases whether they are ORA- errors or any other.
So another useful feature and observation from my side.