This is a neat one. I found out last night that I cannot restart or shut down either of my Macs if my wife's account is still logged in. In order to perform either function, I have to log onto my wife's account and log it out before it will allow me to either restart or power down the computer. If I try to do so while both accounts are logged in, I will get the usual prompt for an Admin name and password, but then it just won't go past that screen. The prompt just keeps coming up to enter the Admin info. Anyone else experiencing this, or have any recommendations? I did an update install on both machines. I updated our iMac with a full retail copy, and the MBP I updated with an UTD disc. Perhaps doing a full erase and install is the answer? Or do you guys think it's just something buggy in SL? Thanks for any help/info!