Currently Being ModeratedNov 14, 2012 5:13 AM (in response to Chris.S)
I would reboot while holding down the Command-R keys to boot into the Mountain Lion Recovery Partition. There I would use Its Disk Utility to run "Repair Disk" on your Macintosh HD that you would select in the left hand column. Then I would run "Repair Permissions" twice. That may solve the problem.
Hope this helps