This was happening to me as well. I have a motorised system with Vbox, and had no problems with a Universal LNB. I recently replaced this with a Unicable LNB. This worked fine by itself, but when I tried to use the Vbox ( with diseqc 1.2 ) it started to crash, sometimes changing channels and sometimes just changing the tuner configuration.

For the last week there have been no crashes. I have fitted an Alps tuner and use this to control the Vbox. It seemed more stable if I selected "Measure motor current" and increased some of the timings in the diseqc parameters. I've also stopped using Tuner A and use Tuner B & the Alp. I still cannot set up my tuner configuration as I want it ( in nimmanager.py there is a comment that this is still ToDo ), but at least it seems stable. Also in the last week I have installed the latest OoZoon image. I'm still trying things out.

My 8000HD is a new model with BCM4506 tuners & I am suspicious of these. I expect most of the developers have older models with different tuners and perhaps don't see any problems.