I got this restarting a new game many times. You will notice that the map size for the last game is smaller than the rest. I used same size each time.
http://dl.dropbox.com/u/15383583/Paul-PAUL-PC-05.23.11-logs.zip
It looks like you jump into each large map and press Ctrl+U to reveal the whole map (which pulls all the worlds graphics into memory), then restart and do the same a few times. Displaying one large map in a game is tough, doing this multiple times in the same application space is very hard on memory. Not to say that our memory usage is perfect, just explaining what is going on.
I'm going to play around with this a bit tomorrow and see if I can reproduce this. Do keep in mind that using the Ctrl+U cheat on large maps is tough on memory, and we will keep working on it on our end.
I got an other error while playing.
http://dl.dropbox.com/u/15383583/Paul-PAUL-PC-05.25.11-logs.zip
Do you remember what this error was? I dont see anything in the logs and the memory usage seems normal (at about 800 meg).