I've just bought a Mutant HD51 to replace my 12 year old Topfield PVR. As this is my first Enigma 2 machine there's obviously a lot to learn, but I have one very basic problem, and that's to do with reception.

There are two C/T/T2 tuners, and we use Freeview. I've manually scanned the tuners for my local transmitter, and that appeared to be successful. However when viewing a HD channel the picture regularly disappears and a message appears saying "Unsupported signal. Check your device output". Once the picture has disappeared it sometimes comes back of its own accord; sometimes it will reappear if I tune to another HD channel. Sometimes it will manage an hour or two of uninterrupted viewing, but yesterday was particularly bad and at one point the picture was disappearing every couple of minutes. When the picture has gone, the sound is still there.

However, worse than this, when I try to select any SD channel there is no picture at all and I get an error message "Tune failed!".

One thing I noticed yesterday is that the SNR and AGC figures for the Mutant are worse than for the Toppy, although I don't know whether this should significantly affect reception. The Toppy was giving me an SNR of 99% for all but one of the SD MUXes (which was 94%), while the Mutant varied from 57 to 72%. The Toppy's AGC figures ranged from 70 to 94%, while the Mutant's were from 57 to 59%.

I have the aerial leads arranged exactly like the Toppy's. I've also tried a different HDMI cable and I've tried using a different HDMI socket on the TV

We had a new aerial installed when we were converted to digital, and since then have used the Topfield for SD and the TV for HD with no reception problems at all, so I'm hoping someone will tell me I have some basic settings wrong, as I'd like to think that a new PVR should work at least as well as my old Toppy. Any suggestions would be very welcome, as I'd like to stick with the Mutant but if I can't do something about this then it's basically unusable. (I'm already in trouble for a failed recording of Antiques Roadshow!!)