quiz module broke the menu list links page

drupal 7.21. fresh installed May 8 snapshot (quiz-6000243). After created quiz, added menu link into the main menu, the menu ->"list links" page can't load properly ( lost all CSS style):../en/admin/structure/menu/manage/main-menu?render=overlay

check Firsfox Web Console, got this message:
Request Method: GET
Status Code: HTTP/1.0 500 Internal Server Error

disabled QUIZ menu links, still the same, then disabled the whole QUIZ module, the menu -> "list links" back to normal.

anyone else encounter the same problem? any idea on how to fix this?

thanks,