A family of Microsoft word processing software products for creating web, email, and print documents.
Since you found copies of FM20.DLL in two different folders, there's something else to check: In Excel, in the Tools > References dialog, click on the Forms 2.0 item in the list. At the bottom of the dialog, what path is shown? If it's the sysWOW64 folder, then try using regsvr32 to register that one, and see if Word will use it. Use the command line shown in my previous screen shot of the Command Prompt window.
The "now you see it, now you don't" behavior of the one in the system32 folder has me mystified. I wonder whether you'll have a better shot if you actually log in as the administrator rather than just using admin credentials from a standard login.