Hello Paul G,
Thank you for reaching out to Microsoft Q&A and informed us about the issue. From my knowledge, this has been a known issue for a while now and here's some methods you can refer to in order to fix the issue:
1. Registry fix:
- Open Run dialogue (Windows + R) > input regedit
- Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\StuckRects3
- Click on StuckRects3 > on the right pane click Settings
- Look for the 7th byte
- If it is showing 01 then update to 03
- Example: "28 00 00 00 FF FF FF FF 01 00 00 00..." Then change to "28 00 00 00 FF FF FF FF 03 00 00 00..."
- Hit OK > Close editor > Restart PC
2. Reset Taskbar using PowerShell:
- Open PowerShell as administrator (Windows + X > Terminal (Admin))
- Input these commands:
- Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"} > Enter
- Stop-Process -Name explorer -Force > Enter
3. Clean boot:
In case the issue still persists:
- Press Windows + R > input regedit > Enter
- Services > Check the box said Hide Microsoft services > Disable all
- Under Startup tab > Open Task manager > Disable all start up items
- Restart your PC
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Haytham - MSFT | Microsoft Q&A Support Specialist.