MacBook Pro won't boot, and then frozen by SBBOD

Question

My MacBook Pro constantly freezes when I try to perform any task.  I frequently encounter the spinning beach ball of death.  Even if I don't see it then accomplishing anything is nearly impossible!  The computer starts up very slowly and displays the gray screen and spinning gear for a prolonged period of time.  Often times the computer won't start up at all and freezes on the gray screen.
My System
15" MacBook Pro - mid 2009
2.8 Ghz Intel Core 2 Duo
4 GB RAM
Hard drive has 370 GB free out of 500
Fixes attempted
Repaired disk permissions
Uninstalled nonessential apps, including antivirus software (Avast was removed months ago)
CPU activity appears ok, frozen processes stopped
Trash emptied
Computer booted in safe mode, still got the SBBOD
This has basically rendered our computer nonfunctional and useless!  For example, it took me nearly 30 minutes just to write this message.  Any help will be greatly appreciated!

Answer 1

Then:
Fixing a Mavericks Installation Problem
How to manage a failed OS X Mavericks installation | MacFixIt - CNET Reviews.
Try these in order:
1. a. Resetting your Mac's PRAM and NVRAM
    b. Intel-based Macs: Resetting the System Management Controller (SMC)
2. Restart the computer in Safe Mode, then restart again, normally. If this doesn't help, then:
     Boot to the Recovery HD: Restart the computer and after the chime press and hold down the
     COMMAND and R keys until the Utilities menu screen appears. Alternatively, restart the computer and
     after the chime press and hold down the OPTION key until the boot manager screen appears.
     Select the Recovery HD and click on the downward pointing arrow button.
3. Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the Utilities menu. Repair the Hard Drive and Permissions as follows.
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu. Select Restart from the Apple menu.
4. Reinstall Lion/Mountain Lion, Mavericks: Reboot from the Recovery HD. Select Reinstall Lion/Mountain Lion, Mavericks from the Utilities menu, and click on the Continue button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.