Tvheadend

Hello,
I have a problem with tvheadend tuning to channels. When I switch to a channel, I seen in the ' status' tab testing, and the bad. Then it switch back to testing and bad, and a couple of times later, it returns running. And I can watch the channel as long as I like.
Sometimes it tunes right away without problems, and sometimes it stops trying. The log is showing:

[[Nov 1 19:40:22 TVHeadend tvheadend¹⁵⁴⁵¹: webui: Couldn't start streaming /stream/channelid//171, No input detected
Nov 1 19:40:22 TVHeadend tvheadend¹⁵⁴⁵¹: subscription: "HTTP" unsubscribing from "MTV"
Nov 1 19:40:22 TVHeadend tvheadend¹⁵⁴⁵¹: subscription: "HTTP" subscribing on "MTV", weight: 100, adapter: "1STV0367 DVB-C DVB-T", network: "Ziggo Brabant Limburg", mux: "Ziggo Brabant Limburg: 762,750 kHz", provider: "Ziggo", service: "MTV", quality: 100]]

I'm using tvheadend 3.5.243~g2b64995~precise on Ubuntu 12.04.3 64bit. Running on vmware ESXI 5.1 with a DD cine c/t in passtrough mode.

What can be the problem here?