I have a WinXP virtual machine under Ubuntu and every user on this Ubuntu should have permission to run this VM. But every time someone runs this VM, the file permissions are set 400 and 600 (accordingly .VirtualBox/VirtualBox.xml and .VirtualBox/Machines/win/win.xml) and ownership is set to the last user. Then i change them back to 444 and 666, so any user could access VM, but I'm looking for permanent solution.
Background: users belong to vboxusers group, Ubuntu 8.04, Virtualbox 4.0.16
EDIT: based on answers so far, i must explain: we need this XP VM only about 5-10 minutes a day, so running it whole time and just connecting to it is not very good solution in our workflow.