Unexplained crashes

[dclare4]

And usually it happens after I've modified the Build_Prod file. It happened in two of the mods I was working on already and this last one all I did was add some buildings from the Crusader_Build file, namely the Muslim Buildings and the Chancellory, Constables Palace, Marshal's Palace, University, Hospital and Academy to the Viking Invasion Buildings. The game loads and it even plays okay but then suddenly and for no apparent reason it crashes to desktop - well not really for no apparent reason, it seems to happen after an invasion occurs. Has anyone else had this problem? All that's been added or modified are the buildings.

Thanks,
Lord Clare