Turn off the File Association in MC, and in Windows.
JimH - Those options are already turned of, infact in all the years I've been using MC it has never been allowed to import anything other than Music Files.
When MC is in Audio Only Mode then in Win Explorer if you right click on an Image File, i.e. a JPG, you are presented with the option to open that file in MC and if you select that option the next thing you will see is MC telling you that a "Playback Problem" has occurred and the reason will inevitably be "The media type 'Image' is not supported".
When shell integration is turned off in MC the option to "open/play in MC" only occurs at the file level, but if it is turned on things get even weirder because Win Explorer and using Explorer within MC do things a bit differently:-
No matter if you select/right click on a File, Folder or Disc Drive MC you will always see the following options:-
Play
Add to Playing Now
More Play Options >
Send To >
Add Folder
Delete*
Rename*
Import Into Library
Customize View...
* Thankfully these 2 are greyed out (not selectable) at the drive level.
And guess what MC acts on the option the user has selected.
Whilst I'm not stupid/dumb enough to want to find out what would happen if I told MC26 to "Play my C: drive" I did open a folder with .jpg's in it and right clicked on one of the images showing in the right hand panel and under "Library Tools" the only option that was not available was "Link Tracks".