I have just bought a Thomson DHD-4000, it works fine for a while but then locks up, sometimes losing picture and sound, sometime just losing picture but keeping the sound. It is in my A/V cabinet, plenty of room around it but with some other kit in there - AV amp, DVD and VCR. I can cure it by leaving a household fan running and pointed at the unit in the cabinet - it will then run all night! Does anyone have similar experiences or is this likely to be a faulty unit? I'll return it, but need to know whether to get a replacement or a refund. Thanks for any advice.