Problem

The ability to copy and/or paste between guest and host machines using Oracle’s Virtual Box stops working.

Quick Solution

Restart the Guest Additions (VBoxTray.exe) in the guest machine.

Explanation

This can be accomplished by rebooting the VM, but I generally don’t want to restart in the middle of doing work, which is probably I’d want to copy/paste in the first place.

To restart the additions on a Windows guest without rebooting the VM, launch task manager on the guest (ctrl+alt+delete). Find the process named VBoxTray.exe. Once found, end the process. You can then start the process again (run VBoxTray).

On a linux guest, the following commands may accomplish the same result however I have not personally tested these.

$ killall VBoxClient
$ VBoxClient-all