Webroot installs itself into ".%programfiles%" not "C:Program Files"

I am a long time happy Webroot customer. I download most installers into my C:SysAdminInstallers directory and run them from there, where the installer asks for the installation directory. No problem, I put in C:Program Files. 
With this Nov. 2018 release of WebRoot, however, things have changed. It overrode my specification and attempted to install itself into the following subdirectory:
C:SysAdminInstallers%program files%RllpdptrqVgdPtGk.exe
I attempt to put in C:Program Files and the WebRoot installer overrode it with %programfiles% as a subdirectory using requested randomized directory and file name.
C:SysAdminInstallers%program files%
Yes that is '%' in the file name. I figure I must be missing some basic concept or be infected by a virus. Yes both my machine and user environment variables are set as follows:
programfiles =C:Program Files
I think the last time I had to set environment variables was sometime in the 1980s with MS-DOS. I say "attempted" because the installation never completes--Webroot apparently looks for itslef in C:Program Files and can't find it, and then restarts installation in an endless loop.