In the interest of avoiding repetitive questions and answers,
here is the beginning of this thread (I think).
Dr. Nico,
It seems to me this is related to your use of a wireless network. Your Win7 machine is hibernating or sleeping, or somehow entering a state which allows the connection to be lost. There is something in your "power options" that is permitting this. I would suggest you follow Bert's suggestions and go through the "power options" to be sure that machine NEVER hibernates, sleeps, or otherwise powers down.
