I recommend to cross check if
- You really have administrator rights
- The extension of the downloaded file type is msi.
If the file type is not msi, download LibO msi file from here: http://www.libreoffice.org/
After the download check if the file type is msi. If not change it to msi.
When upgrading from an old version like 2.8.2 to 4.3. or 4.4 I recommend to save the user profile with a different name to be on the save side for the case that something can go wrong. If you run into troubles. uninstall the old version completely and make a new installation. Thereafter move back folder by folder from your old installation and test if all works.