I couldn't find a "PC Clean Expert" at Download.com.
I can see Registry Clean Expert or PC Clean, but neither of those are PC Clean Expert.
So, please tell us more.
1] Did you download this file from Download.com http://download.cnet.com/2000-20_4.html
2] Please provide the URL web page link to the Product Description page.
3] Did you download from the "Your download will begin in a moment" page, or did you click any advert on a web page?
4] Which anti-virus are you using?
When I tried to download PC Clean Expert my anti-virus program popped up a message that the download page or the setup file contains malware. CNET should take this program off its website.