Switch everthing off, unplug everything from the mains, and carefully remove the scart-leads one by one from the Sagem D-Box, your TV, DVD Recorder etcetera. Then visually check each scart-plug on each scart-lead for bent pins. If you find any replace that lead (cheap ones are usually o.k.). Then carefully re-fit each scart-lead making sure that the plugs are properly located and have not gone-in crooked. Doing these things can cure all sorts of faults. Also beware of scart-leads where not all of the pins have been fitted to the scart-plugs (as supplied with some set-top boxes). If you do not fit these in the correct scart-sockets they can produce various faults. Finally switch everything back on and I hope you hear sound again. Good Luck.
Tom Derby., July 2008