VirtualBox: Pressing some key few times fast causes an event storm

[Yuri]

I run Ubuntu guest on FreeBSD host.
I am in Open Accessories/Terminal app

I get this quite often: when I press some button fast few times it gets 
pressed endless number of times. This can be Enter after some command. 
Or Up/Down on some large file in vim. Guest behaves like I pressed this 
button infinite number of times and stops responding.

Trying to close the guest window causes window manager to ask if I would 
like to terminate the virtualbox application altogether. This means that 
this window isn't responding.

Is this a known bug?

Yuri