I had obtained Air Cars from somewhere, then I inadvertantly made a mistake for the final dump that everyone has. It never mattered before, because the checksum hack disguised the problem. Fixing the wrong bit allows it to work once again. Here's the new version:http://www.sendspace.com/file/ylhe43
Also, the removal of the checksum hack has broken most of the betas and homebrews in my collection, and of course all .rom files.
My collection of jaguar software is quite extensive, so I can do extra testing if needed.