norton download contains a virus and has been deleted..please help

I just tried to download Norton anti virus and after it had finished it said it contained a virus and had been deleted.  I know that Norton does not contain a virus, so I figure my computer must.  So then I tried to download Norton power eraser and it did the same thing...please help!  The reason I started this is a few of my keys have stopped working all of a sudden.  Not all, not even all in a row...just a few in the middle row.  So the first thing I wanted to do was eliminate the possibility of a virus, I had purchased Norton for 3 computers and had meant to load it in this one a while ago, and silly me put it off.  Now I am stuck.