I also have a problem of wifi on my 70b eReader.
It has been working correctly until a few days ago when it does not recongnize the box already registered. After questions to the company they proposed to re create manually the box : no succes and to reset the whole eReader since the begining : no succes again.
Did it happened to someone with a good solution ? I just bought the machine in june 2012. Could it be possible to find another way to go on internet without the wifi ?
(I am on windows 7).
Thanks for any help.