You will receive a pop-up notification that says "A new instant message has arrived. Would you like to view it? " Click Ok to view the message and/or respond. Click Ignore to go back to it later. If you click Ignore, you can view the IM by clicking the flashing IM icon.
To disable these notifications, click on the IM icon, and Options. Remove the check in the box that says "Enable Pop-up Notifications".
