Why do i get a up pop up about my search change notification has been blocked by another user?

Question

yahoo has blocked an attempt by another program to change my settings, when i just have yahoo

Answer 1

This is an anti-spyware notification.  Many spyware / malware programs will change the default search engine on your browser to their site.  Yahoo anti-spyware blocks this action.

If you're getting this popup often, you have some spyware on your machine that you need to eradicate using one of the spyware removal tools available online.  Good luck.