I wish that the usual solution to this common problem were kept pinned at the top of the three Extend It! forums as I think I've answered similar post several times this past week:
Make sure that in your module's settings (Page Settings), the "Cache Time" is set to 0. You may also want to set the Cache Duration to -1 in the Host-->Module Definitions for this module or in the module's .dnn manifest file. The -1 signifies that the Cache Time will be set to 0 AND the option of changing the Cache Time will not be shown on the settings page of each instance of the module.
The tip off to this being the solution is "wierd", non-working or intermittant postbacks from buttons and other asp.net controls WHEN the user is not logged in or does not have edit privileges on the module vs proper operation otherwise.