I had a "Device control violation".
I plugged in my external harddrive and I noticed my laptop blanked for a second meaning my desktop icons disappeared and I saw a blank DOS window pop up and disappear. After a few seconds everything went back to normal. I ran my Trend virus scan and it said all clear (green checkmark). Afterwards, I unplugged my device and it warned me not to unplug because it was "in-use" only I had nothing open for it to be in use. I took the hard drive and plugged it into my work laptop and their virus scan - Also Trend - immediately through a message: "Threats/Violation Found" - Device Control violations - Officescan detected unauthorized access to devices connected to your endpoint.