Can my computer catch a virus even if a download is not complete?

here's the deal i tried to download the latest version of msn about a week ago and i was in some kind of a hurry so i went to hippo-downloads.com and clicked on the download real quick.when it was like at 50 percent my virus detector said that the file i was downloading could harm my computer and since that day videos sometimes freeze and it takes me longer to log into certain pages.