I've been stewing for several days over how to respond to this. I am more than willing to make your job easier by finding the bug myself, but trying to do so blindly by firing data at a demo installation without any sort of information about what sort of condition would typically produce this error message seems, um, inefficient. All I wanted to know is what the error message means, as a way to start the bug hunt. If it's a generic message that just means, "gee, there's a problem in the data somewhere", that's fine, but if it in any way localizes the problem that would be a big help.
I certainly don't mean to whine here. Fact is, I can be a lot more helpful with a little useful advice than I will be if I get a rote response that asks me to take a much longer route to a solution.