1.Yes the computer belongs to me and me only
2.I am the only one as I have it password protected.
3.NO router policy in my life.
4.I have tried everything.
Even GRV3964 is having the same problems.
When John B mentioned some time ago that the problem may lie with the Service Provider limiting access to other Internet addresses, via their own address, during on-line Multiplayer Games...!
I checked this with my Service Provider who assured me that they were aware of this point and that in my case all their ports were open to allow on-line Multiplayer games activity between addresses...no problem...

Paul....Simple DSL Modem...(no Router)....and a Phone line.... 8-)...!