Digidesign has encountered problems with SCSI Manager version 4.3, which is part of System 7.5. Symptoms include clicks, pops, and drop-outs that appear to be written to disk. If you encounter these problems, try the following: In non-Power Mac systems, simply remove the SCSI Manager Extension. In Power Mac (and 840AV) systems, SCSI Manager is built-into ROM. In this case, the workaround is to format Pro Tools drives with a non-SCSI Manager-based disk utility program (such as SilverLining v.5.4), or to format it using a non-Power Mac system. Note that you should only format or optimize drives when they are connected to the Mac SCSI bus. For more information, please contact your drive or disk utility manufacturer.