Here’s the errors from the log for you
[31-Mar-2013 08:37:48 UTC] WordPress database error Duplicate key name 'pollip_ip' for query ALTER TABLE wp_pollsip ADD INDEX pollip_ip (pollip_ip); made by activate_plugins, activate_plugin, do_action('activate_wp-polls/wp-polls.php'), call_user_func_array, create_poll_table
[31-Mar-2013 08:37:48 UTC] WordPress database error Duplicate key name 'pollip_qid' for query ALTER TABLE wp_pollsip ADD INDEX pollip_qid (pollip_qid); made by activate_plugins, activate_plugin, do_action('activate_wp-polls/wp-polls.php'), call_user_func_array, create_poll_table
They are expected as there’s no validation as to which version is already installed, so its trying to add the index each time the plugin is enabled, instead of only when its moving from an old version to the new one.