Your question has completely changed context now. First you wanted to know how to download "Microsoft Security Essentials" and, if I take you literally, you now say you were using "MSN Security Essentials" (assuming that was not a typo, not sure that product ever existed) and "it" stopped functioning.
Now you say that "it" is blocking your download from the sites given.
First - "it" cannot black the download from that site on another computer. Get a USB thumb drive or USB drive of some sort and download the following things on another computer and save them on the USB drive to bring to this computer...
Install SuperAntiSpyware first. Update it and perform a full system scan. Remove anything and everything it finds. Rebooting if/when necessary.
Then install MalwareBytes and update it and perform a full system scan, removing anything and everything it finds. Rebooting if/when necessary.
Then perform an online scan with the eSet Online Scanner.
Then try to install Microsoft Security Essentials. It should be able to install over itself *if* what you had running was actually it and not some malware.