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.
Adservice sneaks its way onto your PC through browser security exploits, or bundled with other malicious software. Once installed on your PC, Adservice parasite will generate a large volume of popup adverts, and may trigger browser slowdowns and crashes.
Technical details (How to remove Adware.Adservice(pop up))