I've just upgraded my Myth box to R5B7. Everything is running just sweet apart from one thing which I only noticed a couple of days after the install. The auto tuning seems to be broken.

Under R5A26 (with the same hardware) it picked up all the channels, under R5B7 it all seems a bit hit and miss, with odd channels missing all over the place (I'm on Freeview free-to-air DVB-T in the UK). I've changed the 4 way signal amp and all the cables, but no improvement.

I manually added the channels, but Myth can't lock onto them on live tv.
However, the Thompson DVB-T stb linked to the Tivo (it's the wifes-don't ask...) plugged into the same amp has no trouble at all...

Am I missing something? Has the DVB code had a revamp? The signal strength is in the 80-90% range, the SNR is 70%+, should that be enough?

The hardware is a Sempron 2600, NF7 nforce mobo, 512 ram, 3 x Avermedia 771 dvb-t tuners, generic Geforce MX400 video.

TIA