Try deleting/disabling the third party applications after a restart by using the application un-installer. If the system operates normally, there may be 3rd party applications which are causing a problem. When you reboot normally, the initial reboot may be slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. The boot up is significantly slower than normal. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear. Shut down the computer and then power it back up after waiting 10 seconds. Disconnect all peripherals except those needed for the test. If the problem is still there, try booting into the Safe Mode using your normal account. Isolating an issue by using another user account The intent is to see if it is specific to one account or a system wide problem. If Back-to-My Mac is selected in System Preferences, the Guest account will not work. Try setting up another admin user account to see if the same problem continues. Do a backup, using either Time Machine or a cloning program, to ensure files/data can be recovered.
