virtualbox 4.2.6 repeating key press on win 7 64 bit

[Harold Chan]

When I turn on a virtual host with 2GB ram Ubuntu 12.10 64 bit, I found that it will affect the host system.

The response of pressing keyboard is slower. Sometimes it will cause repeating keypress even i just press the keyboard once.

The effect is just like:
teeeeeeeeeeeeest

When I close the VirtualBox, the problem goes away.

Host: Windows 7 64 bit, Virtualbox 4.2.6

Any clues? Thanks!