Sometimes users face Outlook keeps not responding error. They must try the following steps:

1. Close Outlook and restart it to see if the issue resolves.
2. If restarting Outlook doesn’t help, repair the Outlook installation. Go to Control Panel, click on Programs and Features, select Microsoft Office, and click on Change. Select Repair, and follow the instructions.
3. Some add-ins can cause Outlook to stop responding. To disable add-ins, go to File, click on Options, select Add-ins, and choose Manage: COM Add-ins. Uncheck the add-ins you want to disable and click OK.
4. The preview pane can also cause Outlook to stop responding. To disable it, go to View and uncheck Preview Pane.
5. Clearing the cache may resolve the issue. Go to File, click on Options, select Advanced, and click on the Empty Cache button.
6. Hardware acceleration can also cause Outlook to stop responding. Go to File, click on Options, select Advanced, and uncheck Use hardware graphics acceleration.
7. If the above steps do not work, try updating Outlook to the latest version.
8. If none of the above steps resolve the issue, you may need to reinstall Outlook.