Unable to upgrade

Hello,
Tried several times to upgrade to latest version of LibreOffice on Windows 8.1 machine.
I am administrator but get error message asking me to re-sign-in as administrator, when having done so error message still appears. Had no problems downloading and installing previous versions.
MS website not very helpful can anyone offer a solution?

Solved it for myself by ‘Clean Boot’.
Seems to be the only way after trying the many suggestions offered.
Thanks to everyone for their help.
triron66