I switched from a PC to an iMac at the end of last year and, in the main, found the transition to be smooth and worthwhile. I now have Mac software for all but OCR, personal finance, and synchronizing my Treo 680. Over the past couple of months, I have found that my security setting 'require password when waking' has been ignored occasionally. Usually, repairing disk permissions has returned things to normal. After updating to 10.5.4, however, I can find no way to restore the password function. As the iMac is in my study, this is a concern when I leave the house but it would be a serious problem were the machine in an office. I've used a variety of OSs over the years, on mainframes and on desktops, but have never come across such a security problem before. Further, having to repair permissions seems wrong to me - is HPFS+ really that fragile?