0x0000000c errors, Can't start in safemode, can't run CCleaner or Malwarebytes

Hi,
I'm running Windows XP Home SP2 on a Dell Dimension DV051. I am experiencing host of problems, which may or may not be connected. I'm not really a computer wiz, by any means.

When shutting down, I get an error along the lines of 'The instructions at ox6a2a2fec reference memory at 0x0000000c.' This dialog stays open for a few moments, and then the computer finishes shutting down.

My network won't connect to other computers in the workgroup.

I downloaded an installed CCleaner, which started fine. I ran the dleaner fist, which worked. Then I ran the registry cleanup (after a registry backup). Quite a few registry errors were detected. I looked through the errors, and selected the ones that seemed safe to fix. I then clicked fix. Ccleaner ran through a couple of them, then mysteriously crashed to the desktop. After this, I could not restart CCleaner. When trying I would get an error message telling me that the path, drive, or whatever could not be found, or that I didn't have permission to access it. The same happened with Malwarebytes in the middle of a full scan. I removed both from the computer, with no issues.

I figured I would try booting into Safe Mode, and seeing if I could install malwarebytes and ccleaner, and run them successfully there. But Safe Mode bluescreens on me after listing all the drivers.

I seem to be systematically shut out of every attempt I make at repairing anything. I was able, however, to install Wise Registry Cleaner (which I found through the free software picks here, and run it, fixing the errors I selected successfully, but I still have all the same problems.

How do I go about fixing this/figuring out the problem?

Also, I have no idea where the OS disk is, so Recovery Console, isn't doable atm.

Any help anyone can give would be great.