Yahoo! has also been criticized for providing ads via the Yahoo ad network to companies who display them through spyware and adware which display on-screen pop-ups, generated from adware that a user may have installed on their computer without realizing it, sometimes by accepting online offers to download software to fix computer clocks or improve computer security, add browser enhancements, etc. As an example, users who have allowed their machine to become infected with spyware will see advertising pop-ups generated from advertising distributor Walnut Ventures, who had a direct partnership with Direct Revenue