oh yea! figured it out! i was screwing around with the new version i was working on incase you couldnt fix it, and i got the same problem again. but this time i figured out that it was the background music causeing the error. as soon as i set it to play the music, it kept giving the error in the map editor and when i tried to play it. in hte sound manager, originally i had a midi as the music, but i deleted the midi n put an mp3 in, but never changed the media file, thats why it crashed. im about to test it now with the "corrupt" version. if you dont see an edit to this post then it worked and its all fixed; in which case, you may want to make a new error message display saying something aboutthe media file instead of tilesets or w/e it said before.