[jeffy162]

If you are looking to set the "zoom scale", just zoom the map to where you like it and then right click the map and choose "Save Map Scale" (not sure of wording, not in-game right now) from the menu. I've found that you only have to do this on one of the maps to have it affect both sizes of the map, both minimized and maximized (those are the proper terms, since Carbonite only uses one map), but it can't hurt to do both, though. Then, when the scale looks "off", just right click the map and choose "Restore Map Scale" from the menu, or you can set a key bind for it. Just open the default key binding facility (esc > Key Bindings) and expand the "AddOns" heading. You'll find the Carbonite key binding options there. Set a key binding for "Restore Mapscale" and you should be done with it.

After you set up your "zoom scale", lock the maps in place. This will stop accidental moving or sizing of your maps. To do this place an "X" in the box in the all the way upper right corner of both map frames.

I don't know what causes the map scale to go wacky, but you can't stop it from doing it. It might be another addon or it could be something that is happening in your game and is local to your machine. I had the problem for a little while, but it cleared up and never bothered me again. I'm still waiting for it to happen again, but it hasn't yet.