I think the answer is quite simple.
The DM 7020 CPU is just not powerful enough and your flogging a dead horse.
It works fine, a DM800HDse, also on IPTV Streams,
And as he told, on another one he has no problems... so this one has the problem... and on my past experience I had exactly the same situation, and it was the 3 big capacitors near to smartcard reader that were deteriorated, needing replacement... and it was going worst to worst, with time.
TS
