When Outlook isn’t working correctly we often tell users to use Safe mode. Safe mode loads Outlook without any add-ins or extensions, the reading pane, or customization (like toolbars). If Outlook works ok in safe mode, then the problem is with an add-in or one of the configuration files Outlook uses.
After closing Outlook there are two ways to reopen Outlook in Safe mode:
1. Hold Ctrl as you click the Outlook shortcut
2. Type outlook.exe /safe in Start menu, Run or the Start Search field.