I downloaded both the LO 3.6.2 installation package and the LO 3.6.2 built-in help installation package from the Downloads page on the LO website.
My laptop is running Windows 7 Home Premium (fully up to date).
The main LO 3.6.2 package installed very smoothly.
The built-in help package could not be installed. Windows showed an error message saying the package was not recognised and my anti-virus software (Norton 360 Premium) said the help package was not safe and immediately deleted it. A second download of the help package also failed with exactly the same error messages.
It is a false alarm. Software installation should be done with antivirus switched off, when it comes from a trusted source. TDF does not spread malware, and packages that are digitally signed by TDF can be considered safe.