Umm no it does not! The image was already embedded in the file. Windows Explorer is merely displaying this data most people do not know about, it does not edit or modify your files. ID3v2 tags have the ability to hold image data.
ID3 - Wikipedia, the free encyclopedia
Then some program is editing my mp3 tags. All my mp3s have ID3v1 tags only. I know this because I go through every new mp3 to make it that way.
logicearth is correct. Windows explorer will only display the info it is reading.
However, if you are using WMP12 for your music library it could be set to update missing info only, or replace all info with what it finds when it does its internet look ups.
I always set the WMP12 options to never check the internet for media info, and never change anything.
Being an avid MediaMonkey fan, i like for MM to do all my tagging and editing.
Its quite possible WMP12 is doing this in the background. I dont think you even need to be actively using it, only that it has the music library location, and does this in the background.
I obviously totally missed the root of the issue, I apologize.
In WMP12, go to options.
In Library Tab, uncheck 'retrieve additional information from the internet"
You can still have Explorer show the album art thumbs if you like, it will not change any tags, just as logicearth said.
Hope this helps.