virtualbox.org

I have a WinXP guest running on a WinXP SP3 host. I have a USB device filter configured for the guest. Every time I start the guest after I reboot the host, when I insert my USB device, I get the "Found new hardware - Virtualbox USB" message on the host and I have to go through the whole process of creating a checkpoint and answering the compatibility question (because the USB driver is not Microsoft certified) and all that. I plug the same USB device into the same USB port, so why does the host have to reinstall the Virtualbox USB driver every time? This only happens after I reboot the host. As long as I don't reboot the host, I can shutdown and restart the guest over and over and don't have to reinstall the host USB driver when I plug my device in. Is this due to some security setting or something on the host?