An update from me. I just tryed to load my next new patrol with the Interiors mod enabled and it CTD'd before the 'Not so long ago...' message. I had previously loaded a save and a new patrol with the OH 3.09 mod with no issues on top of my existing mods, of which there were many, some quite demanding. I'm using XP 32bit without any boot.ini switches or .exe patches.
One thing that I've noticed is that any previous crashes I've had have been related to kernel.dll, but in the case of the interiors mod it's always ntdll.dll. I don't know if this is any help or whether it is the mod alone that causes it or a combination of all of them, but it seems strange that I get a different error for interiors.
I hope there is a way to fix it but otherwise I'll have to wait until I upgrade my RAM and get W7.