Sorry about that -- not really sure why, but I haven't been receiving notifications that people have replied to this thread.

Mike, did your issue get resolved? I'm not sure if there might be a timeout problem with the blacking out. I noticed that this does happen occasionally with maemo mapper using my tiles. I suspect that this is because my images are pngs with 4 full channels and therefore tend to have a larger memory footprint than most overlays. Anyway my suspicion is that maemo mapper is crashing with a certain amount of memory usage, not sure though. I did see the black screen followed by a maemo mapper crash, but I reopened it and it did fine.