Well, Yahoo is trying to make some profit with those little annoying ads at the bottom of your Y! window and you don’t like it. Here is a way how to remove it. By mean, you will stop support them.

1. Download this file (.reg text file) to your computer and execute it.

The .reg file you’ve just downloaded edits most registry values related to the ads in Yahoo Messenger from HKEY_CURRENT_USER\Software\Yahoo\pager\YUrl, replacing the data with a dummy asterisk. Here’s the list of string values (only the first two are essentials):

Messenger Ad
Y Content
Webcam Upload Ad
Webcam Viewer Ad
Webcam Viewer Ad Big
Webcam Viewer Ad Medium
Change Room Banner
Conf Adurl
Chat Adurl

2. Delete this file:
C:\Program Files\Yahoo!\Messenger\cache\urls.xml

If you download new version of Yahoo, repeat these steps and you should be fine. Enjoys the new chat!