I'm not sure exactly when this happened but the activity list has stopped showing up in the Activities tab for all of my contact records. The number of activities seems to be accurate and I can add activities but they simply do not show up.
I ran patched the Activities.php file and unchecked 'Enable CiviMail to create activities on delivery' as per this page. I also emptied the contents of template_c and then emptied the Drupal cache but none of the steps helped.
I'm running Drupal 7 and CiviCRM 4.4.3. Any thoughts on what might be happening?