The "Microsoft Outlook keeps freezing or not responding" error can be caused by different factors. It includes a slow or overloaded system, compatibility issues, outdated software, and corrupted data files. Here are some steps you can try to resolve the error:

1. Sometimes simply restarting the program can resolve the issue. Close Outlook and then re-open it to see if the problem has been resolved.
2. Outlook add-ins can cause the program to crash or hang. Disable any add-ins by going to "File" > "Options" > "Add-ins". Select "COM Add-ins" and click "Go". Uncheck the box next to each add-in and restart Outlook.
3. If the problem is related to a corrupted PST file, you can try repairing the file using the Inbox Repair tool (scanpst.exe). To run the tool, navigate to the location of the PST file, typically in the Documents > Outlook Files folder and double-click scanpst.exe.
4. You may try uninstalling and reinstalling Outlook. Make sure to back up your data before proceeding.

If the issue persists after trying these steps, it may be related to a more serious issue with your computer or the Microsoft Office installation. In this case, you may want to seek the help of a technical support specialist.