Follow the steps listed in that Microsoft Knowledge Base article to run Scan PST. Important: In many cases, Scan PST requires more than one pass to fix a corruption.Run Scan PST repeatedly, until it reports that there are no more errors.This article describes some of the most common reasons that cause Outlook to become unstable, crash, hang or freeze.If you are experiencing issues with your Outlook, try these items one-by-one and hopefully one of them will help.Herein we’re discussing easy working solutions to fix common Outlook problems that cause the email platform to reach the “not responding” stage. On a Windows machine, any time an application or process gets stuck in operation or reaches a deadlock for resources, the “not responding” message appears on the title bar of the application’s window.In such a stage, there’s little you can do except wait for the process to exit the stuck stage or quit. Imagine you’re in the middle of an important mail chain and have just sent a crucial input.
Although the vast add-in majority is designed to help you improve your Outlook experience, sometimes 3rd party Outlook add-ins can cause Outlook crashes or they can simply conflict with each-other.
What "Not Responding" usually means in Outlook is that it is just too darned busy working at whatever it is you've asked it to do, to actually respond to your mouse click or keystroke.
Windows is trying to give your mouse-click or your keystroke to Outlook, and Outlook is just too busy. That's where things get kind of odd and interesting.
Most of the times, Outlook stops responding due to a very large mailbox file that it's causing Outlook to require more resources than the computer can offer.
Weight Diet for Outlook can restore your Outlook speed and stability by decreasing & compacting your mailbox file, making Outlook to require less resources.