Okay i have a virus of some sort that whenever i click something says i have viruses infecting my computer with a dangerous virus that needs to be cleaned before it crashes.

This and i also have porn popping up whenever i google or yahoo search anything. A big picture will appear saying" Your computer has been infected by a dangerous virus. some results was changed by porn advertising.you must clean your system immediatly to prevent it. download the newest antivirus softwear.

someone please help