since we have been on Digital i have noticed that although, in gerneral, the picture and sound is much crisper there is far more noticeble interference and it does not always occur during bad weather. Some of the smaller channels (ABC1 for example) become unwatchable due to glitching, hanging pictures etc.....
I did see that some people may require an arial upgrade to cope with the signal so that might be worth looking at.
i read that although the digital bandwidth is much greater than the analogue signal, because of the number of channels each channel actually has less comparable assigned bandwidth, so any problems are amplified.
If you are 'losing' channels then that sounds like software problem.