I'm not convinced that there is any Malware on your computer as all the logs have come back Clean, It could be that it was there but is there no longer.
What I would like you to do is open up the message again in the action center and select "archive this message". Then see how the computer behaves for the next day or two and see If the message returns. I doubt it will
Also because it was detected by Windows I would like you to check with one of their tools.
Click on the Windows orb and type "MRT" into the box, You should see a program on the open list. Open this program and run it and see if it finds anything.
MRT came back clean. Like you say, it certainly is odd that the infection hasn't since turned up so I will go back to using Windows as normal and wait and see if anything unusual happens.
Thanks very much for all your help and advice. It is clear you have invested a fair amount of time in solving / investigating my problem and I feel I can trust what you have told me so thanks!
