After upgrading to Logic Pro 7 or later, you may get messages that ask you to locate IR files when you open a Logic 6-created song that contains instances of Space Designer. Despite asking you for the location, the navigation dialog used to locate the file (or files) will default to the correct location for the file in question.
This happens because the default location for IR files has changed with Logic Pro 7. A complete set is installed at /Library/Application Support/Logic/Impulse Responses. Songs with Space Designer instances that refer to the old default location (/Applications/Logic/Impulse Responses) will exhibit this issue.
You can resolve the issue by selecting the same IR file from the new location for each instance of Space Designer and then saving the song.
This document will be updated as more information becomes available.