Game crashes taking a town

[cougarcar]

Anyone know why I get this.  I re-installed from stream and re-extracted 4.1 file for the mod (used the same save game)   I can't take any town as it crashes on the final battle screen in the lords hall.  All my guys die

script warning on opcoad 1734:  invalid agent id 631 line no 3
mission template mst_besiege_inner_battle_castle trigger no: 77 consequences.

I am using M&B W 1.174,  edit mode off, load textures on demand.  Battle size 200

thanks