I think the problem came when updating to a certain SVN (CVS) version which modified the xml configuration file. Since I'm not listening to the radio on an everyday basis I couldn't find when it did happend.
Yepp.
The difference between RC3 and RC4 is that i manually scanned for the channels in RC3... But in RC4 i selected my city and got the channels automatically in the setup.
I have just made a clean reinstall of MP RC4 and same result.
When I press the radio channel nothing happens. And then MP stops responding and crashes.