avast 5 pro failed to start

Hi. I have downloaded avast 5 Pro and I am ready to insert my license. When I try to open the program, I get the message, “Application failed to start because the side-by-side configuration is incorrect”. Please advise. Barbara

Is/was there another av present on your system?
If so, delete it completely before installing avast

I ordered Avast Pro 5.0 and when the license was sent to me it opened to this message

License.avastlic is not a valid avast!license file