When I set up LR8.0 or LR7.6 or LR8.1, I did not find errors that you said.
But I believe that everything will not all right, I do not know your installation condition and do not know the steps your setting up,such as the path you set, and selected which option, but there are not mind.
You can download LoadRunner installation guidance from web(try search from google or other searching applications), many enthusiastic friends have ever uploaded it to the web.
Best wishes for you!