Subject: bug#30043: 25.3; C-M-e inserts euro character

From: Eli Zaretskii <[email-masked]>
Date: Sun, 14 Jan 2018 05:34:22 +0200

> From: Tomas Nordin <[email-masked]>
> Cc: [email-masked]
> Date: Sat, 13 Jan 2018 23:10:43 +0100
> 
> > Does it help to set w32-use-fallback-wm-chars-method to a non -nil
> > value in Emacs 25.3?
> 
> Yes, that removes the problem.

So I guess you somehow have a keyboard which doesn't fit the new
keyboard input code introduced by Emacs 25, and need to use this
fallback variable to avoid the problem.