When I open Yahoo Messenger, I can't see any chat activity, though I can access the rooms and see others listed.

Once you've selected a Chat room, you'll be brought to the Chat room window where you'll see your Yahoo! IDlisted as well as the Messenger Chat Administrator. You won't see anyone else listed in the Chat room until you've passed the verification process. To do this you'll need to click the verification link given in the Chat room window. The "Chat Room Verification" window opens, where you can enter the word verification text (please note that this text is not case sensitive).

If you don't see the "Chat Room Verification" window load when clicking on the verification link, this is maybe because you currently have pop-up blocker software installed. To confirm that pop-up blocker software is interfering with loading of the "Chat Room Verification" page, please hold the Ctrl key down while clicking the verification link and the new window should load. Now all you'll need to do is to enter the word verification text and click Submit