You could try this. Disconnect the mains. Take the boxes apart and carefully remove the hard drives. Connect them to a computer and see if windows "sees" them. Click, Start, Computer (win 7). If they show, they are working. If you have recordings you want to keep dont format, but you could try formatting and writing to them on the PC. If they dont show bin them and replace with new/used HDD`s of the same size, should be 160gb.
Replace them in the boxes and try them. Simply removing/replacing them can sometimes fix the problem. (This happened to me!) You will have to let the boxes format them or the new/used drives before they can be used. To do this go to Thomson`s web site. The details are there somewhere. Or the drives are FULL of recordings. Try deleting some stuff. If all this fails you have indeed got two very expensive freeview tuners. Good luck
thomson fan, June 2012