Does anyone know a work around for this problem:

I downloaded the three files, have placed them in the same folder, but when I go to install, the installer says that the source files are corrupted and it will not proceed further. I have checked that there is not an extra number (1) on the downloaded files, and even re-downloaded the installer package, but it still will not work.

At this stage, I don't want to download the 2+ GB of data all over again only to experience the problem again.