What you are describing sounds like the device is losing sync with the computer. Is the light on the front blinking red to blue when this happens? Due to your self proclaimed lack of pc skills, this issue may be better for a support ticket. One thing that can help with windows 7. Go into device manager in the control panel, and look for the firewire device (1394 iee). Right click your firewire device, and select properties. Go to the driver tab, and select details. There should be a driver in the next box labeled legacy. Select that as the driver to use. Then restart your pc.
Without anymore system detail, it will take a bit to troubleshoot back and forth, so if the legacy driver does not help, then open a support ticket.