hmm, i really abandoned the error checking in MapView but there are working checks for easy errors, give it a try! (link is in my signature)
Try loading the map view mapview and saving it again, there´s a chance my parsing doesn´t care about the error and the error will be fixed if you just open and immediately save the file again. (make sure you make a backup of your map before)
Furthermore try to replace paste all the plot info into a working map so you can isolate the error to the plot reagion or the player, map, team regian etc.
If the error is in the plot regian you can use MapView to resize the map (mayb 50%), save it and if it loads you´ll know the error is the part of the map that´s been cut off. Repeating that procedure you could find the error pretty quick..
good luck