Have you tried safe booting & repairing permissions? ie: reboot whilst holding down SHIFT key until you see Safe boot message. Beware a safe boot usually takes much longer to finish booting & for some people considerable time. After it's finished starting up, go to Utilities folder & open Disk Utility & repair permissions. You could also try using the Disk Utility from the start up disk & choose to Repair disk (but don't repair permissions from the startup disk.)