Was it Hamster Free Zip Archiver?
You said you had a serious problem installing a program from CNET. Just underneath the green button which says "Download Now", there's a hyperlink which reads "Direct Download Link". Which one did you click on?
IF it was "Download Now", I would (strongly) suggest using the "Direct Download Link" from now on. It seems to be less problematic. If you DID click on the Direct Download Link........ I don't know what else to tell you, short of reading this post.
Continued success with Avast!