cant say im not part of the development team, just trying to help here and there.
then again compiling a hello world example should not need anything but a compiler with standard libraries. that its looking for SDLmain had me a bit baffled, as SDL is more like directx.
i cant say for sure what might be the reason youre having problems newer encountered something like that before.
did you be any chance install the new codeblocks over the old one ? theres been quite a few mistakes like that recently and it does not work mostly because the mingw compiler that comes with it is a newer version and not compatible with the old mingw.