A bug has been fixed in Avast and Avast security applications that set registry keys that blocked applications from running in Windows 10. Windows 10 users began to complain [1, 2, 3, 4, 5] that they were unable to launch Microsoft Office and other applications. Avast has also provided an URL to download this fix now. Users might also receive an error, such as, ‘Windows cannot find ‘C:Program Files (x86) Microsoft OfficerootOffice16WORD.EXE’
Source: https://www.bleepingcomputer.com/news/microsoft/avast-fixes-bug-blocking-programs-from-starting-in-windows-10/