The aerial was checked out earlier this year, because (during the fierce winter we had) the masthead preamp got ripped off. I spoke to the installer at length about this and he said the orientation is correct and he checked it with his box.
We then feed the signal into an 8-output Antiference distribution amp in the loft, which feeds several TV+FM sockets around the house.
I know a lot of these people are cowboys but this was a "reputable" firm and I assume they know which way the antenna is supposed to be pointing. I also asked him if there is a better one we can buy and to his credit he didn't try to take another 100 quid off me; he said we already have a good one.
The issue with the channels coming up differently on almost every retune has always been there. The Humax started rebooting only a few months ago. It was originally discovered only because programmed recordings did not get recorded (immensely irritating). It was later that we noticed it doing the "stopped video but sound running on for a bit". There are plenty of reports on google of this but no solutions.
Of course it is completely daft that a PVR should crash just because it isn't getting the "right" signals. It's crap software. But as stated above there has to be another factor in play otherwise a large % of the UK would be getting it too, because loads of people are potentially receiving signals from multiple directions. That (picking up sidelobes etc) has been a problem since the earliest days of analog TV.
The Sony 1080P TV (bought 2012) works fine, except sometimes the reception is not good (breaking up video). But lately it has been fine. We did notice the problems in the summer, mostly. Also its Freeview receiver doesn't do HD which is why we use the Humax as the receiver, and output to the TV via HDMI.
FWIW, I had hoped that the Humax would do its documented functionality a lot better. For example it never properly accessed the networked HD (Buffallo 2TB), on which I have stills (jpegs) and videos. It finds the jpegs but only some within a given directory (folder) so clearly there is something buggy in the file list enumeration code. Also its loading speed is painfully slow, on ~10MB jpegs. It could do load-ahead but it doesn't which makes it useless for a slide show. The only way to use it for that would be to generate custom-downsized files, say 1080 pixels wide, just for the slide show. It plays some video formats but not others; I know it can't do them all but all these boxes are based on a ripoff of Linux and you can get every codec going for that... I spoke to Humax about this and the guy was fairly honest and said that's the way it is... I got the impression they finished off the code and moved to the next project, leaving behind a load of known issues. It's a pity that if you are happy to use a (low-end) PC for a PVR, you can get superb functionality which is superior in every way to the Humax - except of course in packaging and straight out of the box working. We have not used the networking for anything of use, though lately with the CFW we were able to decode and convert to Mpeg some TV programmes which was a slick feature.
Sorry Trev - it did run for an hour this morning on Ch4+1, after the factory defaults