If Outlook gets stuck loading with the "Processing" message, close the app, and launch it in safe mode to try fixing this problem using the following steps:
- 1. Use the Windows key + R keyboard shortcut to open the Run command.
Type the following command and press Enter to start Outlook in safe mode: outlook.exe /safe
Click the OK button.
2. Close the Outlook (Safe Mode) app.
Once you've completed the steps, launch the app normally one more time, and Outlook should no longer get stuck with the "Processing" message.