FreeView

[#1]

A friend next door is experiencing a weird problem ?
He has a potable TV with separate Freeview box , last week he lost his sound on TV so he acquired another TV .
Ok so far ,, now what has  happened  is the whole TV & freeview box freezes , power it all off , and when you power ON you return to same frozen picture ? 
so he got a new Freeview Box , & i gave him my spare Digital aerial .
Now it still freezing up  the remote will not control anything so have to power off 
this happens about twice a day so it runs ok for so long then freezes again 
Any ideas

[#2]

Very susceptible to interference including the new 4G band in certain areas.
I had a similar issue and after a week of pulling my hair out traced it to a PC with the side cover that had been let off. It was spewing out EMI and killing the Freeview signal.
A possibility - maybe try bringing his television round to your house and see if that cures it.