Hi I've found that if I change the integer value after the section 5 pointers in the main mdr header from 0x1d to 0x1c then small maps appear to work fine. Unfortunately large maps crash on startup with that value. Of course I don't know how to select between the two values yet, so I can't check anything in. I will experiment to see if I can tell what the difference is, but if anyone has any ideas please let us know. It is also true that all of the values after the section pointers apart from section 15 are unknown, so they are all worth investigating. ..Steve