I suspect some Disk corruption.
Bootup holding CMD+r, or the Option/alt key to boot from the Restore partition & use Disk Utility from there to Repair the Disk, then Repair Permissions.
Reset Password 10.7, 10.8, 10.9...
Then Reset your Keychain...
Just to be clear, you are using Mavericks 10.9.2, but posted your question in Tiger discussions. Please confirm which OS X you are using so we can properly address your issue.
One option to try regardless of version is to create a new User and see if the problem goes away. Testing in a new User will quickly tell you if the problem is system wide or if it’s your User’s folder that contains the problem. For help visit:
Use new User to test for problems