Are you running the latest version?
Running the latest version of TSR is always a good idea regarding performance, stability, features, etc.
If you or your users are not running TSR 6.4.7 or newer, we strongly recommend that you upgrade as soon as possible.
With the new way of getting the installation kit, it should only take you 1-2 minutes.
You can see how to upgrade here: Upgrading the TSR Outlook User Agent
You can check which version you’re running by going to Outlook add-ins > TSR > About.