We have seen similar behavior before. Please follow the below resolutions:
1. Open Computer Management. ( Right click on "My Computer" and select "Manage" OR Open control panel, go to "Administrative Tools" and then select "computer management")
2. Go to System tools--> Device Manager. Expand "Ports (COM & LPT)
3. Uninstall the sepam driver that gets installed when you connect the mini usb cable to your computer. Once the driver is uninstalled completely, restart your computer.
4. When the computer is restarted the device driver for sepam is installed again and will help you communicate to the relay.
Update windows by going to control panel--> Windows update.