http://www.topuptv.com/help+centre/setup+and+troubleshooting/#Problems+Recording
The above seems to be a fairly common fault. Mine has just done it yesterday. It seems poor that the advice given on the above page doesn't help (nothing will actually record i've found and can't reformat as still have items to watch on it.)
This all seemed to happen after a problem with recording a program and hasn't been fixed by rebooting the box either.
The recording ability of these boxes doesn't seem to be very good as it can't cope with recording two sequential programs on the same channel (it cuts them in the wrong place on almost every occasion as far as i've found).
BH
October 2010