Norton 360 diagnostics error report of inoperable hardware devices on my Windows 7 PC

I run Norton 360 diagnostics and get the following message:

!Inoperable hardware devices

Problem: Norton 360 has detected inoperable hardware devices

Recommendation:  You may want to configure these devices.  Run Device Manager to properly configure these devices.

When I click on details, it advises that Null is the problem.  The message says the device is not present, not working properly, or does not have all of its drivers. and says the plug and play ID is Root\legacy_null\0000.

There is no device in device manager named null. 

Since I don't seem to have a null device, is there a way to remove this plug and play id of root\legacy_null\0000 that will prevent norton from giving me the above error?

 

In my device manager, there are no devices with problems.  All indicate that they are working properly and have the latest drivers.