[drupal-devel] Problem with drupal_get_messages()

Hi, I am having a problem on a site where the messages from drupal_get_messages() is not being deleted once they have displayed. I have checked and drupal_get_messages() is deleting $_SESSION, but session is not being updated to reflect the change. I am not sure why this is happening, or how I should proceed to resolve this problem. If anyone can shed some light which can help me to resolve this issue it will be most appreciated. Thanks. Gordon.