Cannot open .chm

Hello, all.

I am using FM 2015 in a Windows 10 environment. I initially thought this is a Windows problem, but my coworker who is using Windows 7 also cannot open this .chm file.

I am publishing a .chm from FM 2015, using the identical files I have been working in for a year. Some time between my previous build on July 26 and the builds I have attempted today, something has changed. Now, when I select View Output, I immediately get an error message. The same thing occurs if I double-click on the .chm file in Windows Explorer. My coworker has had the same result. This is the message:

Has anyone else encountered this problem? Better yet, has anyone solved it? I have, of course, rebooted.

Thanks.

--Nancy