I have another suggestion now. Try creating a second user account with admin rights from your Windows control panel and see if you can install the software with that account.
Also, you may want to run Windows Update again until you do not see any .NET framework installations. I want to make sure you have the most up-to-date installer package and it seems to install in order (example: version 4.0 then 4.5, etc).
Let me know if either of those suggestions work.
