virtualbox.org

Installed Win10 Pro into VirtualBox VM. Most basic functionality seems to be working. Although Start button icon changes colour when the mouse hovers, there is no action on left click. Right-click does bring up a menu and selecting options works fine.

Hi You can try this 1. Launch Task manager

Press the [Ctrl] + [Alt] + [Del] keys on the keyboard at the same time, or right click the Taskbar, and select Task manager.

2. Run a new Windows task

When the Task manager window opens, click the More details option to expand it, then select Run new task from the File menu.

3. Run Windows PowerShell

When the Run new task dialog box opens, type powershell, tick the box for Create this task with administrative privileges and click OK.

4. Run the System File Checker Type sfc /scannow

or you can check this https://techsherlock.com/windows-10-sta ... t-working/

Hope this will solve your problem

Also try disabling Settings > Personalization > Colors > Transparency Effects in your Windows guest.