Also in order to help avoid this problem, if you've got one big object and a bunch of little pieces something more like this:



That will actually work with them all selected at once because the boolean union code sorts the objects by size and makes sure to start doing the processing with the largest one.

But that kind of sorting does not help for the kind of "stacked side by side" type thing like your case.

In the future I hope to be able to tune it up so that it is not sensitive to the order of processing at all though.

- Michael