Problem viewing a C: drive using Firefox

[charlie6067]

Windows 7 64-bit machine

When I need to examine a client's C: drive in Lansweeper, the attached message displays asking that a Lansweeper Shellexec plug in be installed. I follow all of the steps, but the message displays again when I try to view the C: drive. I also used the suggested link in the 4/7/17 Knowledgebase article https://www.lansweeper.com/kb/11/firefoxplugin.html, but no change.

One thing I noticed is that the Lansweeper plugin never appears in the Plugin section of Firefox. It always displays in the Extentions section. Can that be the problem? If so, how to correct.

Thanks everyone,
Charlie
charlie6067