Multichoice hangs on going to next question

I have several issues:

1. Quiz multichoice questions won't proceed immediately (i.e. I have to click multiple times on an answer and the next-button to move to the next questions). Moreover, regardless of the 'Allow resume' option, the quiz takes off where I stopped it last time.
   • I feel it be something like browser caching. Does anyone knows a source for the problem?

   Similar issues:
   http://drupal.org/node/1491364
   http://drupal.org/node/1579468

2. The Quiz Default configuration won't be saved with the mentioned browsers either. Both from the admin menu as from the ticked 'Remember my settings'-checkbox in a main quiz it generates the following error:

   		PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '436' for key 'PRIMARY': INSERT INTO {quiz_user_settings} (uid, nid, vid, aid, pass_rate, summary_pass, summary_pass_format, summary_default, summary_default_format, randomization, backwards_navigation, keep_results, repeat_until_correct, feedback_time, display_feedback, takes, show_attempt_stats, time_limit, quiz_always, has_userpoints, allow_skipping, allow_resume, allow_jumping, show_passed) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9, :db_insert_placeholder_10, :db_insert_placeholder_11, :db_insert_placeholder_12, :db_insert_placeholder_13, :db_insert_placeholder_14, :db_insert_placeholder_15, :db_insert_placeholder_16, :db_insert_placeholder_17, :db_insert_placeholder_18, :db_insert_placeholder_19, :db_insert_placeholder_20, :db_insert_placeholder_21, :db_insert_placeholder_22, :db_insert_placeholder_23); Array ( [:db_insert_placeholder_0] => 436 [:db_insert_placeholder_1] => 1712 [:db_insert_placeholder_2] => 3620 [:db_insert_placeholder_3] => 0 [:db_insert_placeholder_4] => 0 [:db_insert_placeholder_5] => [:db_insert_placeholder_6] => redactie [:db_insert_placeholder_7] => [:db_insert_placeholder_8] => redactie [:db_insert_placeholder_9] => 0 [:db_insert_placeholder_10] => 0 [:db_insert_placeholder_11] => 0 [:db_insert_placeholder_12] => 0 [:db_insert_placeholder_13] => 0 [:db_insert_placeholder_14] => 1 [:db_insert_placeholder_15] => 0 [:db_insert_placeholder_16] => 0 [:db_insert_placeholder_17] => 0 [:db_insert_placeholder_18] => 1 [:db_insert_placeholder_19] => 0 [:db_insert_placeholder_20] => 0 [:db_insert_placeholder_21] => 1 [:db_insert_placeholder_22] => 0 [:db_insert_placeholder_23] => 1 ) in _quiz_save_user_settings() (line 4221 of /sites/all/modules/hacked/quiz/quiz.module).
   	

   Similar issues:
   http://drupal.org/node/1538808

Does not work
IE8 on Win XP
IE8 compatibility mode on Win XP
Chrome 23.0.1271.97 m on Win XP

Does work
Chromium 20.0.1132.47 on Ubuntu
FF 15 on Win XP