On the Dashboard, there is a section called Recreational (see below):
The 5 rows for Games, Instant Messaging, P2P, Social Networking, and Streaming are all based on the default application groups by those names (found in Configuration > Applications > Application Groups). If any of those application groups are deleted from the device, then the row will become empty in the Recreational section. For example, the screenshot below is taken after the Social Networking application group has been deleted:
For this example, to add Social Networking back to this table, simply create another application group called Social Networking from Configuration > Applications > Applications Group.