I agree about wipe everything but before that you need to make sure it's ur pc
1 - Borrow a laptop or from a friend/parents and use it for some time using ur regular stuff, GMT2 and CPA
If you still get the messages then its not the pc, if you don't get it, get rid of the pc or the hard desk at least
2 - if u still getting the message, then its time to stop all IM activities, just shut down the laptop and pc and plug off internet cord
If you still get the messages, you are innocent, if not, its something to do with IM tools/activities. Nulled tool, vurenable tools..etc
3 - If you still get the message, the yiur internet port is hacked by a neighbour which I think is weak probability
I believe this should lead u directly to the problem
Source: Years of exprience in hacking