What is icuuc67.dll and why is it creating an error message?

Acrobat has run perfectly for me for years. But now, suddenly, when I attempt to highlight text using the Comment Highlighter function, I get the error message:

Adobe Acrobat: Acrobat.exe - Bad Image

C:\. . . \Adobe\Acrobat DC\Acrobat\icuuc67.dll is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support. Error status 0xc000012f."

I don't recall what media I may have used to install Acrobat and I am my own system admin (or have been to date!) and I have no idea what to do. . . .