In my house I use an Edimax router , there are three computers who use this router but only two are wireless. one of them is a hp pavilion ze4900, it is usually stationed at the same spot in the house. the thing is that this spot speed and signal strength change all the time , it is usually alright but once every couple of houres it disconnects. why are there fluctuations in the signal , the house is pretty still and there are no electronic interferences on the way ?