Digital Performer project files have their Mac OS file type code set to PERF and their creator code set to MOUP. If you have Digital Performer project files that have become damaged and they can not be opened because they are dimmed in the File menu > Open dialog, the problem may be that their file type and creator codes were set incorrectly. You can reset them with Mac OS X's SetFile command (included with the Developer Tools package) or with a third-party application like Quick Change, FileBuddy, or FileType.