Failures when Upgrading from Drupal 5.9 to 6.4

Issue Summary

When attempting to upgrade from Drupal 5.9 to Drupal 6.4 I receive the following error:
update.php warning:

“# user warning: Unknown column 'timezone' in 'field list' query: UPDATE scheduler SET publish_on=publish_on-timezone WHERE publish_on<>0 in /home/stilbla0/public_html/drupal/sites/all/modules/scheduler/scheduler.install on line 79. # user warning: Unknown column 'timezone' in 'field list' query: UPDATE scheduler SET unpublish_on=unpublish_on-timezone WHERE unpublish_on<>0 in /home/stilbla0/public_html/drupal/sites/all/modules/scheduler/scheduler.install on line 80. # user warning: Can't DROP 'timezone'; check that column/key exists query: ALTER TABLE scheduler DROP COLUMN timezone in /home/stilbla0/public_html/drupal/sites/all/modules/scheduler/scheduler.install on line 81. # user warning: Table 'stilbla0_StillTruth.amazon_item' doesn't exist query: ALTER TABLE amazon_item ADD mpn varchar(128) in /home/stilbla0/public_html/drupal/update.php on line 69.
--Drupal database update

Farther down the page there is a failure listed:
Failures:

“scheduler module Update #6100 * Failed: UPDATE {scheduler} SET publish_on=publish_on-timezone WHERE publish_on<>0 * Failed: UPDATE {scheduler} SET unpublish_on=unpublish_on-timezone WHERE unpublish_on<>0 * Failed: ALTER TABLE {scheduler} DROP COLUMN timezone
--Drupal database update

Information:
• Upgrading from Drupal 5.9 (Scheduler 5.x-1.16) to Drupal 6.3 (Scheduler 6.x-1.2 ).
• Running http://example.com/update.php shows that even with the Scheduler module disabled in 5.9 before the conversion The scheduler module: was going to upgrade (upgrade number: 6100).

Questions:

2. How fatal is that error? Is it a show stopper from my site going live?
3. Should I do any database edits or drop tables or whatever? (I'd honestly rather not, my Sql fu is pretty weak.)