New unit model causing ctd in campaign but not battle

[hacon]

I hope someone can shed some light on this strange error.
I am running the Alex.exe and trying to add new unit models to the DMB text file.
I have 230 entries at present.

When I run custom battle I have no problem.
When starting the campaign it immediately CTDs
If I remove the new unit from DMB all is fine again.
I have tried deleting an unused entry from DMB and adding the new unit again but get the ctd in campaign start.
Thinking there was a problem with the new model/texture , I added a vanilla model to the DMB but still got the CTD. Removing vanilla entry and all was well again.

I have run out of things to try,
the dmb entries are well below max, maybe I have reached a performance limit of my video (running on laptop 128mb o/b memory, 768 mb ram 1.4 pentium M.

The puzzling thing for me is why the custom battle is ok and not the campaign.

[Aradan]

In both cases the only unit of your army was the new one?

[hacon]

In both cases the only unit of your army was the new one?

The ctd did not occur at a battle in the campaign but when clicking the campaign start button, the campaign map was not displayed.

[hacon]

Update,
I have found that if I move the texture and model to a different directory from the mod directory and update the DMB file to refer to their new location the problem goes away.

This solution is hardly satisfactory and I am still no nearer in finding the real cause.

puzzled of catalunan grande

[Aradan]

So, your game only has a problem when the files exist in the mod's models_unit folder?

[hacon]

Update
I have now backed out to last working module
reapplied all new units and no problems
still clueless why this was happening particularly why custom battles were ok but campaign ctd'd.
thanks to all who gave my problem some thought.