I was trying some SDL applications (fuse-sdl, dosbox) under Raspbian without X. With an HDMI monitor they run without problems. However, when I switched to an old TV with the analog video cable whenever I run an SDL program the screen turned blank and I couldn't do anything but to connect remotely or switch the PI off. I noticed that the problem was the overscan settings I had used:
When I commented out all the above the problem was solved!
Does anybody knows which is the actual cause?