HD becomes Read-Only and "Unapproved Caller: SecurityAgent may only be invoked by Apple Software" Error Message Displays
I'm running Mavericks on a mid-2009 MacBook Pro, and every couple days my system becomes really slow and my HD becomes read-only, and when I restart I get a gray screen and the error message "Unapproved Caller: SecurityAgent may only be invoked by Apple software."
Usually after restarting my system, things return to normal, but sometimes it takes 2-3 restarts. I've tried migrating to a different user and resetting permissions, using DiskUtility (no errors found) but nothing works. It's gotten to the point, that I don't trust using my system anymore. Any suggestions on things to try would be very much appreciated! I'm about ready to give up!
MacBook Pro (13-inch Mid 2009), OS X Mavericks (10.9)