“All of them were coming from the same ISP.”
Thank you for this clue. I was wondering what this BK and Rose Mary are.
Now when you said: “All of them were coming from the same ISP,” now understand what may have happened. I was transferred to my Head-Office last month. And nature of my work also somewhat changed. To avoid virus problem, I put a requisition for a second computer exclusively for net-related work. Office gave me an old computer. I am posting from this computer as I have somewhat relaxed schedule. I don’t know who was using this computer before me in this company of over 3000 people!
Abiather: it is most probable that every computer at the 'Head-Office' uses the same ISP. And it also has nothing to do with who used your computer before.