How to fix virtualbox's copy and paste to host-machine?

If your guest OS is ubuntu then running following two commands in ubuntu terminal should help:

$ killall VBoxClient
$ VBoxClient-all

On a Windows XP guest, I can kill "VBoxTray.exe" using the Task Manager (Ctrl+Alt+Del), then restart it from "Program Files/VirtualBox Guest Additions".

In the Oracle virtual box setting go to

Settings > General > Advance

There is a an option Drag n Drop. Select the direction you want to copy the text.