Well, the old keyboard trick didn't work. I finally found one with that old purple male part, but the female port was missing on the back of my computer. I don't know when they stopped making those ports and everything went to USB, but obviously it was before my computer was made.
My computer is back to normal now! I'm honestly not sure how, as I said I was using Hiren's BootCD. I first used it to run a very, very long memory test and everything passed. So then as I said in a previous post, I was using it to access Mini Windows XP and get my files off the computer should I have to reformat or do a clean Windows install. Then just now I booted up with the Hiren BootCD again and chose "Boot Windows XP from Hard Drive." I never thought it'd work, but after choosing this, Windows ran CHKDSK. When it restarted itself it booted from the Hiren BootCD again, and once again I chose to boot Windows XP from Hard Drive. Believe it or not, it booted up just like normal.
I am of course thrilled. I suggest Hiren's BootCD to anyone having similar problems. And, I'm of course now going to set up my external HD to back up automatically.