ive found on win 11 that along with winmx.exe, channel rejoiner, and mxmoni need to run as administrator as well... basically anything "winmx" needs admin rights or it wont work right..
that said i havent actually used the installer in quite a few years as i keep a rar archive of my winmx folder that i always extract into the 32bit program files directory.. it goes all the way back to win7 32bit and has even been used on linux, but has been updated and re-archived over time..
this is actually best practice after you first install winmx because all of the settings you change and all the new filetypes that need to be added.. this is especially true if you use opennap and have usernames/passwords saved... just be careful what you pick as a username.. being too sarcastic with winmx' demand that a UNIQUE username be chosen can end with.. interesting results...