Microsoft says uninstall Windows 11 KB5074109 to fix Outlook POP, PST hang, as 2026’s first update causes havoc

If your Outlook Classic freezes or hangs when you use POP accounts or deal with PST files, you’ll need to remove Windows 11 KB5074109 or use webmail. In some cases, third-party apps can also become unresponsive if they save files to cloud storage, such as OneDrive. These two issues are apparently related to a single core problem.

It’s very rare for Microsoft to admit that it messed up, but the January 2026 Update is a disaster, as it continues to break features in Windows 11, including something as basic as Sleep mode (S3) on older PCs. In our tests, Windows Latest found that the update causes a black screen, resets the desktop background, breaks File Explorer customization, among other problems.

KB5074109 is a mandatory update that began rolling out on January 13, 2026 and it installed automatically on our PCs. Your PC is using this update if you see OS Build 26200.7623 / 26100.7623 / in Settings > System > About or winver.

Meanwhile in other news: Windows 11 continues to lose market share to Windows 10. Oh dear Microsoft - when you go for a cash grab, and your code is garbage - you reap what you sow!

UPDATE TheRegister 260126: Microsoft probes Windows 11 boot failures tied to January security updates. Some machines are failing to start after security updates, prompting yet another Microsoft investigation

www.windowslatest.com