V9.com is a browser hijacker, which is promoted via other free downloads, and once installed it will change your browser homepage to v9.com and default search engine to search.v9.com.
This in itself is not considered malicious as there are many legitimate programs that change these settings as well. What is considered malicious, though, is that it will also append the argument http://www.v9.com/ro/newtab?si=41460...t=true&tid=293
to random Windows shortcuts on your desktop and your Windows Start Menu.
V9 Search will display advertisements and sponsored links in your search results, and may collect search terms from your search queries.