@phiscribe
I'm was also having 500 errors problems when trying to upgrade from 6.2 to 6.4. Initially, I also had the same error that you were receiving during the update. If you look through the error garbage, you'll notice references to the Analytics code that 000webhost has been automatically adding to everyone's web pages. This creates the initial error during the Drupal upgrade. You can read the announcement how to disable it here:
Disabling analytics code
So, I disabled the analytics code, and no longer received the error during the update. That being said, I was still get the same 500 error after upgrading. The only way I fixed it was to upload my old .htaccess file from my backup. I really don't know the technical reason why this works, or if there are any repercussions from this, but that was the suggestion from someone on the Drupal forums, and it worked for me.
http://drupal.org/node/300450