Intermittent Controller Disconnects.

This isn't a software issue, but rather a hardware issue.

1. Cable integrity
   
   The first item to check is, of course, cable. If you're using the HCU100/200 USB controller, check the cable and the firmness of the connection, both on the cable side and on the computer side. USB connections, like all removable cable connections, are based upon friction contact. The metal can wear and after time, the connection will not be firm. Even small vibrations can cause a disconnect. This is rare, and most USB connectors are good for 50,000 connections.
   
   If you're using an older HCS type controller with telephone cable and a RJ11 to DB9 adapter/Serial USB adapter, the same hold true. In addition, occasionally, the RJ11 to DB9 adapter will develop and issue and will need to be replaced. This adapter is available from www.telescriptwest.com/Products. Also, the USB2SER adapter is an active electronic device and is subject to the same hazards as all active electronic devices. A repoacement for this device is also available at www.telescriptwest.com/Products. Note that problems with the USB2SER adapter are more often "GO/NO GO", not intermittent.
   
   
2. Device Manager -- USB Power Management
   
   For reasons known only to Microsoft, the USB ports are not covered in your selection of ACP Power Managment, but rather, each USB Device can be suspended independently if there is no keyboard or mouse activity. This clearly happens when you're using the controller.
   
   To fix this, open Device Manager. Most easy way is to use the "Search Box" in Win7 or Win10, and type "device manager". Select the app from the list.
   
   Expand "Universal Serial Bus controllers. For each item in the list, double click, then look for a "Power Management" tab. On this tab, UNCHECK the box that reads "Allow the computer to turn off this device to save power". Click OK and repeat for each item in the list.
   
   Here's a link to a similar discussion on the web, nicely illustrated and annotated:
   
   Disable USB Power Management
3. Power Options / USB Selective Suspend
   
   In addition, the computer may suspend individual USB ports under a feature called "Selective Suspend". Again, this is NOT affected by your general power settings. 
   
   In the Windows search box, type "power options". In Windows 10, you can just right click on the Window Icon (lower left) and select "Power Options", then select "Additional power settings". 
   
   For prompting, you should have "High Performance" checked. Click "Change plan settings", then "Change advanced power settings". Find "USB Settings/USB selecting suspend" and select "Disabled".
   
   Here's a link to another article on disabling "Selective Suspend", geared to Win10, but equally applicable to Windows 7:
   
   Disable Selective Suspend