I got a notice to upgrade LibreOffice from (I think) 5.0.1 to 5.0.2. I went to their site and downloaded the .msi file. When I tried to run it, it uninstalled and deleted the old version. Then it failed because it couldn't write to C:\Program Files (x86)\LibreOffice 5\program. Nothing I can do enables me to change that; the security settings require permission from SYSTEM for any alteration. I was left without the old version *or* the new one.
Setting as duplicate of bug 94216, but if you get a moment please pull a verbose msiexec.exe install log and post there. *** This bug has been marked as a duplicate of bug 94216 ***