Mission.sqm addons problem!

[Ace]

I recently donaloded an M4 addon that I used in my mission. Now I don't think i want to use that addon any more as the BIS M4 is OK and its quite a big file for people to download.

So I edit EVERY unit that has this weapon, save it. Open up the mission SQM and delete it from the addons list. Save it again and exit, delete the addon from my directory and decide to test it has worked.
I now re-load the mission in the editor and it says "cannot load mission, missing ADF_M4 addon"

What? I deleted it from in game and the SQM?

I'm pulling my hair out here! Whats going on!

[CrashnBurn]

If the addon uses units that carry the weapon, then editing the units won't work. It will still look for the addon. You have to replace the units with different ones.

[Ace]

No these are just normal soldiers...
What I think the problem is, is:

On my system (windows M.E) when a notepad file becomes too long it become a wordpad file.

So when my mission becomes quite big the misson sqm turns into a wordpad document. OFP can read it but i think it can only be altered by saving in the eitor as if you try to edit it in wordpad you can't save it as a SQM file because theres no option to select "all files" in the drop-down menu.
If that makes sence, so wen saved in wordpad I don't think it becomes a proper SQM file, its readable and changeable in game but not out of game.