Mouse suddenly stops working in Ubuntu (running as guest in VirtualBox)

Arch Linux, KDE Wayland, same issue. After I put the Windows full screen, I am unable to click anywhere. I can't click either on the dialog Window to close the virtual machine.

I think that it is an issue with Wayland. I resolved It by uninstalling VirtualBox and installing VMWare. It works very well.

Go to virtual box -> File -> Preferences -> Input

Disable [] Auto Capture Keyboard

It's the only solution worked for me after fiddling a few hours.

VirtualBox version : 6.1
Host : Manjaro Linux 21 ; Kernel 5.10 ; KDE plasma 5.22 ; Wayland ;
Guest : Windows 10

My Situation: Ubuntu 21.04 - > Ubuntu Virtual box instance -> VPN and connected to a windows box via Remmina.

I noticed, the mouse would stop working. I couldn't click on anything within the VM as well as the actual virtual box application on my main ubuntu pc. The only thing I could do is kill the vm session by clicking on the X on the top left. Once I did this ( i saved the state of the vm ). I was able to click in the application once more.

With Ubuntu 21.04. Wayland is the default display server. Switching back to XOrg seems to fix the problem I was experiencing.

I tried everything I found but the only thing that worked for me was to change the Graphics Controller setting to VMSVGA in the Display menu.

I had this problem recently and I solved it by just quitting the machine by pressing Host + Q (i.e. RightCtrl + Q in my case). You are given the option to save the machine state so your work won't be lost. When I started it back up, it worked fine.

sudo pkill VBoxClient
sudo VBoxClient-all

That worked for me. I think it is easier than searching processes.

I've been having that problem for months, even with drag and drop disabled. Also triggering mouse integration did not help. This FINALLY fixed it for me:

Go to your VM and change the Settings > User Interface to NOT show the mini-toolbar in fullscreen mode

Source: meeas on virtualbox forums

You still can access the menu with a keyboard shortcut: Host + Home

I notice this problem since probably the last few months with VBox 6.1.x. I run Xubuntu 20.04 on MacBook Pro. I feel the issue might be related to double clicking mouse somewhere faster than the system can react (why it sometimes reacts slowly I don't know). Once that happens, basically clicking mouse on any place has no effect at all. But one work around I found is to click the "right mouse", in my case the two-finger click, in a terminal or in an editor or some place, then a menu pops up. You then left click elsewhere to dismiss the menu, then the mouse works as normal.

+++++++ Recently as I have been trying to find out about a problem related to slow menu reactions with Android Studio running on Xubuntu, as I documented here, I found the cause of the two issues are one: display scaling with VirtualBox. I've got a solution/workaround which also eliminates this issue.

Update: As suggested in other answers, as a quick fix first try just right-click with the mouse. If this does not help, try killing the VirtualBox drag&drop processes as described below or in other answers.

Full/Original Answer:

The problem might be caused by VirtualBox drag&drop (d&d) problems. If this is the case, it can be solved by killing the VirtualBox d&d processes.

• Open a terminal (Ctrl+Alt+t does it for me) and find the d&d processes e.g. by: ps -ax | grep VBoxClient, resulting e.g. in (among other entries):

  1429 ?        S      0:00 /usr/bin/VBoxClient --draganddrop
  

• Then kill all processes which contain this text: VBoxClient --draganddrop e.g. for process number 1429 by: kill 1429

I got some hints for this solution on: https://www.virtualbox.org/ticket/14903

If this does not help, try turning off and on again "Mouse Integration" (via the menu of the VirtualBox).

Further, if the problem keeps recurring, consider disabling VirtualBox drag&drop altogether.