hi chewie.
I suggest you to download again the patch5.1: probably you have downloaded it from the old broken links, last week we made new upload working good.
freeforumzone.leonardo.it/discussione.aspx?idd=8375546
If you have Vista:
Locate the map.rwm file in BellumCrucis5-data-world-maps-campaign-imperial_campaign and click "compatibility files", then delete the map.rwm
then Locate the map.rwm file in BellumCrucis5-data-world-maps-campaign-custom-full and click "compatibility files", then delete the map.rwm
start a new campaign.