Karlito 0 Newbie Poster

Okay well, today I started my computer as I normally do everyday. Yesterday everything ran well and there were no problems. But today when I start up this box says "Your computer is infected!" and when I click it, it opens some program called "Zinaps Anti-Spyware 2008". This has happened a long time ago as well but that program never popped up. When this happened I did system restore and when i would start up my computer again the message would be gone and wouldn't appear ever again. Why is it appearing again? When that program scans my cpu it says i have 5 spyware but my anti-virus doesn't pick anything up. What can I do??

Regards, Karlito