Well I finalled managed to solve my tuner problem. It turned out the dm800 wasn't supplying enough voltage to the LNB. I managed to fix that by increasing it in tuner settings menu(advanced mode).
Now the problem is when Configuring for diseqc mode(simple mode), There is no option to increase the voltage anymore. So back to square1 although I know now this is software problem.

any input?

after several days of work, I found a new problem
MY tuner sometimes doesn't respond and shows zero SNRl. I upgraded to the new firmware, it worked for 10 min then stoped working again. I am getting tired of my dm800 with all the bugs...........

I recently owned the dm800 and I have 2 major issues with it:

1)Sometimes it refuse to power on when I attach the power adapter. ie: the oled display remains off. I have to plug/unplug the power cable several times before it works

2)Choppy playback with HD channels after 20sec. Gets macro blocking and green blocks all over my screen. Is this due to:
CPU Overheating or Tuner overheating or Power adapter failure to provide enough power.....

Any help??? tkx.

I am experiencing exactly same problem. I have to plug/unplug the AC several times before OLED lights on and the boot process start. This is extrmely annoying as I thought I burned the receiver first time it happened.