47PFL6907T/12, sw QF1EU-0.150.48.13

I have now seen on several occasions that after using EPG or teletext, screen goes black after returning to normal TV. Sometimes "No video signal" can be seen. If I change channels up/down, picture returns for a few seconds and then goes black again. TV must be switched off and then on again to get the picture back.

Is something like this a known issue?