Message: 'entries starting by initial initial' does not substitute for 'initial'

Fixed in this morning's version, thanks. Should be rolled by Drupal in the next 12 hours.

In the meantime, just replace the '1' at line 1556 (the menu entry for this path) by a '2' and rebuild your menu.

Having the same problem, although line 1555 says 'page arguments' => array('g2_entries', 2),
Using g2 6.x-1.0 on Drupal 6.19.

Line numbers are not the same in 6.1.0. In that version, the same bug appears at another line. If you do not want to use the latest dev version (which is likely best), but keep using 6.1.0, the line to modify is line 1547. Replace:

 $items[G2PATHINITIAL .'/%'] = array(
    'page callback'    => 'theme',
    'page arguments'   => array('g2_initial', 1),
    'access arguments' => array(G2PERMVIEW),
    'type'             => MENU_CALLBACK
  );

with

 $items[G2PATHINITIAL .'/%'] = array(
    'page callback'    => 'theme',
    'page arguments'   => array('g2_initial', 2),
    'access arguments' => array(G2PERMVIEW),
    'type'             => MENU_CALLBACK
  );

But, really, you should be using 6.1.dev, not 6.1.0.

One other thing, not G2-specific: when you add comments to a closed ticket, remember to reset it to active, otherwise the maintainer won't ever see it if he misses the initial notification by the system.