The message, "There are no video capture devices on your computer", usually indicates the capture device has failed and needs to be reset.  If the capture device is an internal card, reboot your computer.  If you are using an external USB capture device (e.g. Pinnacle Dazzle device) close the recorder, unplug the device from the USB port, wait a few seconds, plug the device back in, wait a few seconds, and plug it back.  This should successfully reset the device and allow you to record.