While downloading Photoshop Elements 12, it wants to download instant shield to remove the software?

While downloading adobe photoshop elements 12, it is wanting to download instant shield to remove adobe photoshop.  I put no to not remove the software.  Adobe photoshop elements will not open, what is the deal?  I don't get it.  Had no problems with Adobe premier,  Help, was I suppose to remove the software?  Makes no sense.  I was trying to install the software.