Freeview Radio Problem

[#1]

I still have a few old TVs using Freeview Set top Boxes, and one of them has developed a strange problem. If I watch the TV programmes, no problem. If I try any of the radio channels (usually Radio 4 or Radio 4 Extra), I get the programme for about 10-15 seconds, then the screen goes blank and the sound stops. If I change to a different radio channel then go back to the one I wanted, I get the programme again, but 10-15 seconds later - same thing. If I just change to a different channel, I get that different channel, but hey presto 10-15 seconds later I lose it. I have tried re-installing the factory default, but not sure what that actually loads, because it seemed to go straight into searching for tv and radio programmes (as if I had asked for an update of  the channels and it did the normal full search).
I have come across the same problem on a tv before (not a set top box but the tv which had a built-in Freeview tuner). The only difference in the symptoms was the tv lasted about a minute before the programme disappeared.
Has anyone of you had the same problem and found a cure - I'm looking for a cure not just get a new set top box - I would like to fix the tv if I can as well as the set top box
Thanks

[#2]

Haven't the beeb moved all their radio programmes across to a separate player?
http://www.bbc.co.uk/radio

[#3]

He's talking about radio transmitted over the same Freeview MUXs as digital TV, not internet radio!
If you have a digital terrestrial TV try tuning it to channel 704.

[#4]

Radio 4 on Freeview is channel 704, so is that the same channel 704 that Jelv is writing about?
I have done a re-tune and some more testing, and the problem on the set top box seems to only be on the BBC channels (Freeview 700 to 710 inc). The commercial radio stations appear to be unaffected.
Another tv with a set top box doesn't have this problem (yet)

[#5]

My Sharp freeview box has developed an identical problem.  Did you find a solution?