OK, after extensive research I found out why I get a file mismatch IE MD5 mismatch when attempting to install dotnet11 through to 20, it's because the file (dotnetfx.exe) that the script is trying to download, from http://download.microsoft.com/download/a/a/c/aac39226-8825-44ce-90e3-bf8203e74006/dotnetfx.exe doesn't exist, and therefore POL will throw a file mismatch.
If possible when something like this happens and the file(s) that are needed for installation of something else do not exist, then please provide somewhere else to download those files.
It seems now, POL is only able to run windows software that DOESN'T need dotnet, which greatly reduces POL's functionality.
Dotnet 1.1 (dotnetfx11) has to installed first then others follow, but if files cannot be found then why put POL up for people to use?
I prefer to use POL instead of a full VM such as VMware or VBox, becdause POL doesn't takes up as much space as VMWare or VBox, but POL just runs the software, IF, the needed files can be found and downloaded.