normal map 8m???

I searched and couldn't find anything about this file. I'm modding w/ 1.02 & BigMap and everything works fine except when loading battle screen - ctd w/ unexpected error and quiting. The obvious - yes the geography txt & db have already been removed. I looked at the system log but the level *error didn't give any information, then I tried again w/ *trace and the final 3 lines are:

system.io] [info] exists: missing BigMap/data/normal_map_8m
[system.io] [info] exists: missing BigMap/data/normal_map_8m
[system.rpt] [error] Medieval 2: Total War encountered an unspecified error and will now exit.

I looked everywhere for this normal map 8m file in vanilla data folder and no such reference. Does anybody know what this file is or how to correct this ctd? Thanks in advance.