While troubleshooting why my PC won't detect a GoFlex base, I found a device/service called MpKsla9443f94 in the Non-Plug and Play Drivers section in Device Manager. It currently is flagged as:

This device is not present, is not working properly, or does not have all its drivers installed. (Code 24)

Google comes up empty. Here is a picture of it:

Any idea what this device is?

Do you use Microsoft Security Essentials?

Yes I do have it installed.

this is the answer. MSE uses this driver.

Are you sure? I have MSE installed and have no such driver...

google/bing for "MpKsl" and look at the results.

It is indeed MSE.

Hmm, wonder why I don't have it...!

Hmm, wonder why I don't have it...!

I went to show hidden devices in Device Manager. This is hidden by default, also are you using Windows 7?

Yup - Win+Pause -> Device Manager -> View -> Show Hidden Devices

And on Win7!