Thanks LemP for the response regarding this old OS.
The RI file actually has readable text:
CreateObject("Wscript.Shell).Run
although I don't recognize it.
I forgot to mention in the original post that I had looked at the Task Manager also, but didn't recognize anything that might have caused the problem.
Thanks to you suggestion about using AutoRun, which showed a "Hybrid" task in the Task Manager that pointed to the problem file, which I didn't see previously. I looked again at Task Manager. And by the way, I didn't see any other posts that mention Task Manager for this kind of problem.
Sure enough, the "Hybrid" task is triggered "At log on of any user", and the Action is "Start a Program" and the Details show a path to the problem file.
I disabled the task, rebooted the computer, and the problem is gone.
I guess the Task Manager was trying to start the "executable" file, didn't know how since is wasn't executable, and so just opened it with Notepad.
Thanks for your response and help; your suggestion about AutoRun was the crux in solving this problem, and I'm glad that I'm now aware of this great application.