Try repair permissions. After every software update, and about every 2 weeks: close all apps and log totally off. Log on, go in Finder, Applications. Utilities, Disk Utility. After the message -getting disk information- select volume (below the hard drive name -upper left corner). Just highlight it. Now look to the lower two things are there near the middle, verify permissions, >click repair permissions. If that doesn't help, restart in single user terminal. Restart holding Apple S. In the terminal type /sbin/fsck -fy over until the file system message stops showing