I started a game on a custom map of the Discworld I'd been working on, with custom rules. I could build my capital and change production no bother. I build a second city and any attempt to change production crashes the game. the same happens with subsequent cities, but not with the capital even after the others have been built. After testing I deduced that this had nothing to do with technologies, and that with the custom rules disabled the problem did not appear. The changes I made to the rules were:

renaming of the civilizations I was using, as well as their cities and leaders
I made sugar available on mountains. I disabled this and it made no change.
I made Ocean impassable, and hiked up the ovement cost for good measure. Making it passable again made no difference.

In addition, I'm using a custom terrain set, but no custom unit graphics. I've changed the years as well, starting at 1 AD. Other than that I don't think I've made any changes.
I'm guessing this is down to something that can't be built in the capital, such as the palace or forbidden palace, but I'm not sure. Any ideas?

I also forgot to mention I'm using an unpatched UK version of Conquests, and that I changed the speacial attributes of the civs.

Edit: I've narrowed the problem down to the game crashing whenever custom rules is enabled, even if no rule changes are made. The maps this happens with are custom maps made with the bmp to bic converter, and then resaved as biq files.

I would certainly try patching to 1.22f and seeing whether that improves things.

I was under the impression that the available patches were US only?

Conquests (and its patches) are international in nature.

Ok, thanks. I'm downloading the patch now, but I've given up and am about 60% through redrawing the map from scratch :)