The only way I was able to install 4.0 (and 4.5) was by using .exes from a non-Microsoft website. After scanning the .exes before installing and running Malwarebytes, Spybot and Combofix after installing I think I can safely say I did not pick up any malware from the installs.
The site was http://dotnetsocial.cloudapp.net/GetDotnet?rClrVer=v4.0
if anyone wants to check it out.
My Windows computer hates Microsoft's website