Adware:Adware (or spyware) is a small program that is designed to show advertisements (in various form and degrees of intrusiveness) on your computer. It often reports personal information back to its owners. As a result your sense of privacy can be violated.
Adware.404Search is a vile adware application that is created and promoted by www.404search.com. Adware.404Search installs itself into Internet Explorer as a Browser Helper Object (BHO). Adware.404Search will log your browsing habits and send this information to its developers. Adware.404Search will then display large amounts of pop-up advertisements that are both insistent and annoying. Immediate removal of Adware.404Search is strongly recommended.
Technical details (How to remove Adware.404Search(pop up))